SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c1562c0fc59412bb22218c905924f21e9c54c4ce741bfcea0200af478553c7d' 
  AND token = 'Cv8OZQyansEvUXsPvbmUjuADqdZIIPXsjj0/WgBkYZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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