SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35f9896130add3896adb851f6cfbf270900c34ac3be2fca8053d5d1473c53186' 
  AND token = 'mQJ8uP8sD2Ht9O4BHB+hLUw7GIDBHcTKhNq4Iw2qpPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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