Eloquent ORM query

I'm creating a login code using eloquent with slim framework and this is my code:

$app = \Slim\Slim::getInstance();
$password =  $app->request->post('password');
$username = $app->request->post('username');

if(\User::where('username', '=', $username)->exists() AND \User::where('password', '=', $password)->exists()) {
  echo "yes";
 } else {
  echo "no";
 }

I always get no with my code. Am I doing it correctly?