SELECT 
  cscart_product_point_prices.product_id, 
  MIN(
    cscart_product_point_prices.point_price
  ) AS point_price 
FROM 
  cscart_product_point_prices 
WHERE 
  cscart_product_point_prices.product_id IN (335, 336, 337, 338) 
  AND cscart_product_point_prices.lower_limit = 1 
  AND cscart_product_point_prices.usergroup_id IN (0, 0, 1)

Query time 0.00210

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "5.61"
    },
    "table": {
      "table_name": "cscart_product_point_prices",
      "access_type": "range",
      "possible_keys": [
        "unique_key",
        "src_k"
      ],
      "key": "unique_key",
      "used_key_parts": [
        "lower_limit",
        "usergroup_id",
        "product_id"
      ],
      "key_length": "8",
      "rows_examined_per_scan": 8,
      "rows_produced_per_join": 8,
      "filtered": "100.00",
      "index_condition": "((`aerokidsshop`.`cscart_product_point_prices`.`lower_limit` = 1) and (`aerokidsshop`.`cscart_product_point_prices`.`product_id` in (335,336,337,338)) and (`aerokidsshop`.`cscart_product_point_prices`.`usergroup_id` in (0,0,1)))",
      "cost_info": {
        "read_cost": "4.81",
        "eval_cost": "0.80",
        "prefix_cost": "5.61",
        "data_read_per_join": "192"
      },
      "used_columns": [
        "product_id",
        "point_price",
        "lower_limit",
        "usergroup_id"
      ]
    }
  }
}