How to set GET param to current Request?

Question

I created a service and it works as well.

A piece of my code from "event_subscriber":

public function addRequestAddValue(GetResponseEvent $event) {
  $request = $event->getRequest();
  $request->query->add(['key' => '123']);
}

And than I try get this param on my Controller all Ok:

$key = \Drupal::request()->query->get('key');
dsm($key); // return 123

But if I try get URL I can see only:

$url = \Drupal::request()->getUri();
dsm($url); //return http://localhoct.dv/patn

What I need do to get URI with GET param?

Thanks