SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97a4a205d78557b385cb2d77f3b56d971e3335d6054ea5a7ce42adf4619ea4e4' 
  AND token = '9umvLcWzRt/jfcJgKOE3fi0YWHxU6qVC1ZoW5QJARls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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