SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '098be3ed2b89a372ffac0d720a19f1efd054a8b261f68f48c5d752d38b3291cb' 
  AND token = '6JK9xVwmfwjv357NXwY2FtA0nRYBdcVrRzd4h+JiGb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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