protected function _initQuery()
    {
        $token = $this->getRequest()->getParam('token');
        $index = $this->getRequest()->getParam('index');

        if ($token === null || $index === null) {
            $this->getResponse()->setHttpResponseCode(400)->setBody('Invalid parameters');
            return null;
        }

        /** @var Sheep_Debug_Model_RequestInfo $requestProfile */
        $requestProfile = Mage::getModel('sheep_debug/requestInfo')->load($token, 'token');
        if (!$requestProfile->getId()) {
            $this->getResponse()->setHttpResponseCode(404)->setBody('Request profile not found');
            return null;
        }

        $queries = $requestProfile->getQueries();
        if (!$queries || !($index < count($queries))) {
            $this->getResponse()->setHttpResponseCode(404)->setBody('Query not found');
            return null;
        }

        /** @var Zend_Db_Profiler_Query $query */
        return $queries[(int)$index];
    }