Erro: Call to a member function fetchAll() on a non-object in

Estou criando uma API com o código a seguir, mas dá a mensagem no PHP de:

"<br />

<b>Fatal error</b>: Call to a member function execute() on a non-object in <b>/home/u649998054/public_html/checkToken.php</b> on line <b>13</b><br />"

 

A linha 13 é o $check = $check->fetchAll();

E no meu App surge a mensagem: "ionic.bundle.js:26794 SyntaxError: Unexpected token < in JSON at position 0

at Object.parse (native)
at fromJson"

O que posso estar fazendo de errado?

<?php

header('Access-Control-Allow-Origin: *');
header("Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept");
header('Access-Control-Allow-Origin: [http://localhost:8100'](http://localhost:8100));

	include('connection.php');

	$data = json_decode(file_get_contents("php://input"));
 $token = $data->token;

 $check = $db->query("SELECT * FROM usuario_app WHERE token=$token");

	$check = $check->fetchAll();

	if (count($check) == 1){
 echo "authorized";
	} else {
 echo "unauthorized";
	}

?>