SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd76d341f5d4e28b05243a90c08eb6f2dd07f8c243e056bd2afeb6aae93299b3c' 
  AND token = 'J4MYP5KP0dBk7oM0oylVbTH1h4hOA1cz7itWS+UlVDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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