SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f15e63cdf78ab709fefa2f3eca31266138acaba8fd9faa75ac3a37d6d86b9444' 
  AND token = '1MzayOgQfHVNHS4EqKQLq1Pw6sxsj9cpgzTmFsJBMn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}