SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a92951f52b093a525f55a36cd57dd00049e7c7918f1eaf0e0eba3d2208802d' 
  AND token = 'hJ0hUwPoOxsN+PpIfhCVjZqHvcqR+dUYVDxOxD/FxCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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