SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868c2118e6e9de4561707ff53df04de52e54a1d511ea77475a13b61eb0abf38b' 
  AND token = 'UGYu9IHURtZyYIglFU5PMQF1RV3f3icxRGMPqAUA1uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00079

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}