Lumen routes problem

Hello. I am new to Lumen and i have routes problem. No matter what i type after lumen.loc(localhost/project url), it redirects on index.php. Here's my routes/web.php file

<?php

use App\Http\Controllers\MailController;
use Illuminate\Http\Request;


$router->get('/', function (){
    return view('index');
});


$router->get('/send_mail', function (Request $request){
    var_dump($request->post());die;
    MailController::sendMail($request);
});

when I input lumen.loc/send_mail or even lumen.loc/"some random letters", it returns view index. Thank you in advance