Adding values to request array in Laravel middleware is a good practice?

I have an authentication middle ware to check the validity of the passed api key. I fetch user id from the database store it to the request array so that the requesting page will get the userid.

  public function handle($request, Closure $next) {

        $key = $request->get('key');

        $user = User::where('token', '=' ,$key)->first();

                if($user != null){

                    $request->request->add(['middlewareUserID' => $user->id]);
                    return $next($request);
                  }
                  else {
                    return response(401);
                  }
    }

Is it a good practice?

I would say this is not necessary in such case.

I would use code similar to this:

use Illuminate\Contracts\Auth\Guard;

class YourMiddleware 
{
    protected $guard;

    public function __construct(Guard $guard)
    {
        $this->guard = $guard;
    }

    public function handle($request, Closure $next) {

        $key = $request->get('key');

        $user = User::where('token', '=' ,$key)->first();

        if(!$user){
           return response(401);
        }

        $this->guard->setUser($user);
        return $next($request);

    }
}

so when there is user for given token you can authenticate user in line $this->guard->setUser($user); and when the token is invalid you return return response(401);

I don't see any need to set this user id to request as you showed.