public function exists($key, $namespace)
    {
        // Get internal used key
        $key = $this->calculateUuid($key . $namespace);

        // Assume it does not exist
        $result = false;

        if ($this->getFromRuntimeCache($key, $namespace) !== false) {
            $result = true;

        } else {
            $value = $this->connection->get($key);

            if ($value !== false) {
                $this->addToRuntimeCache($key, $value, $namespace);
                $result = true;
            }
        }

        return $result;
    }