SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '617dec2097fe429b45e37b7cde663dc3747f918722cb796cf1b0c5858e45596b' 
  AND token = 'lNyQchRcr03zRmT6oT9mGQB0DZokea1dUvopZ8ZSuzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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