SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84c634e290d99c819251ee3f6d7e3247643bcc64f7a4b81373298035fbe4257f' 
  AND token = '9KXdS+vdgM613uybuHFn5e8JGzKmVjbkT6XUUTZY/4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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