SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e4831a4fc238cd446ebca662a254d57af94c6039cae2cefe6299589655dd1ff' 
  AND token = '8CTMB/9MXaaRKz5GZvW2NsgWqRnJLLyMasi7WHBhESU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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