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SELECT 
  lang.name, 
  IF(
    cscart_ult_language_values.value IS NULL, 
    lang.value, cscart_ult_language_values.value
  ) as value 
FROM 
  cscart_language_values lang 
  LEFT JOIN cscart_ult_language_values ON cscart_ult_language_values.name = lang.name 
  AND company_id = 1 
  AND cscart_ult_language_values.lang_code = lang.lang_code 
WHERE 
  lang.lang_code = 'en' 
  AND lang.name IN (
    'social_buttons.facebook_cookie_title', 
    'social_buttons.facebook_cookie_description', 
    'social_buttons.pinterest_cookie_title', 
    'social_buttons.pinterest_cookie_description', 
    'social_buttons.twitter_cookie_title', 
    'social_buttons.twitter_cookie_description', 
    'social_buttons.vkontakte_cookie_title', 
    'social_buttons.vkontakte_cookie_description', 
    'social_buttons.yandex_cookie_title', 
    'social_buttons.yandex_cookie_description', 
    'social_buttons.facebook_cookie_title', 
    'social_buttons.facebook_cookie_description', 
    'social_buttons.pinterest_cookie_title', 
    'social_buttons.pinterest_cookie_description', 
    'social_buttons.twitter_cookie_title', 
    'social_buttons.twitter_cookie_description', 
    'social_buttons.vkontakte_cookie_title', 
    'social_buttons.vkontakte_cookie_description', 
    'social_buttons.yandex_cookie_title', 
    'social_buttons.yandex_cookie_description'
  )

Query time 0.00860

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "12.65"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "lang",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "lang_code",
            "name"
          ],
          "key_length": "392",
          "rows_examined_per_scan": 10,
          "rows_produced_per_join": 10,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "10.39",
            "eval_cost": "1.00",
            "prefix_cost": "11.39",
            "data_read_per_join": "3K"
          },
          "used_columns": [
            "lang_code",
            "name",
            "value"
          ],
          "attached_condition": "((`aerokidsshop`.`lang`.`lang_code` = 'en') and (`aerokidsshop`.`lang`.`name` in ('social_buttons.facebook_cookie_title','social_buttons.facebook_cookie_description','social_buttons.pinterest_cookie_title','social_buttons.pinterest_cookie_description','social_buttons.twitter_cookie_title','social_buttons.twitter_cookie_description','social_buttons.vkontakte_cookie_title','social_buttons.vkontakte_cookie_description','social_buttons.yandex_cookie_title','social_buttons.yandex_cookie_description','social_buttons.facebook_cookie_title','social_buttons.facebook_cookie_description','social_buttons.pinterest_cookie_title','social_buttons.pinterest_cookie_description','social_buttons.twitter_cookie_title','social_buttons.twitter_cookie_description','social_buttons.vkontakte_cookie_title','social_buttons.vkontakte_cookie_description','social_buttons.yandex_cookie_title','social_buttons.yandex_cookie_description')))"
        }
      },
      {
        "table": {
          "table_name": "cscart_ult_language_values",
          "access_type": "ALL",
          "possible_keys": [
            "PRIMARY"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 10,
          "filtered": "100.00",
          "using_join_buffer": "hash join",
          "cost_info": {
            "read_cost": "0.26",
            "eval_cost": "1.00",
            "prefix_cost": "12.65",
            "data_read_per_join": "3K"
          },
          "used_columns": [
            "lang_code",
            "name",
            "value",
            "company_id"
          ],
          "attached_condition": "<if>(is_not_null_compl(cscart_ult_language_values), ((`aerokidsshop`.`cscart_ult_language_values`.`lang_code` = `aerokidsshop`.`lang`.`lang_code`) and (`aerokidsshop`.`cscart_ult_language_values`.`company_id` = 1) and (`aerokidsshop`.`cscart_ult_language_values`.`name` = `aerokidsshop`.`lang`.`name`)), true)"
        }
      }
    ]
  }
}

Result

name	value
social_buttons.facebook_cookie_description	Facebook cookies enable Facebook-related functionality, such as Facebook button on the product page. Here is <a href="https://www.facebook.com/about/privacy/previous" target="_blank">Facebook privacy policy</a>.
social_buttons.facebook_cookie_title	Facebook
social_buttons.pinterest_cookie_description	Pinterest cookies enable Pinterest-related functionality, such as Pinterest button on the product page. Here is <a href="https://policy.pinterest.com/en/privacy-policy" target="_blank">Pinterest privacy policy</a>.
social_buttons.pinterest_cookie_title	Pinterest
social_buttons.twitter_cookie_description	Twitter cookies enable Twitter-related functionality, such as the Twitter button on the product page. Here is <a href="https://twitter.com/en/privacy" target="_blank">Twitter privacy policy</a>.
social_buttons.twitter_cookie_title	Twitter
social_buttons.vkontakte_cookie_description	VK cookies enable VK-related functionality, such as VK button on the product page. Here is <a href="https://m.vk.com/privacy" target="_blank">VK privacy policy</a>.
social_buttons.vkontakte_cookie_title	VK
social_buttons.yandex_cookie_description	Yandex helps us display the buttons of multiple social networks (for example, on product pages). Here is <a href="https://yandex.com/legal/confidential/" target="_blank">Yandex privacy policy</a>.
social_buttons.yandex_cookie_title	Yandex