public function find($serializedAuthToken)
  {
    $authToken = $this->deserializeToken($serializedAuthToken);

    if($authToken == null) {
      return null;
    }

    if(!$this->verifyAuthToken($authToken)) {
      return null;
    }

    $res = $this->db()
                ->where('auth_identifier', $authToken->getAuthIdentifier())
                ->where('public_key', $authToken->getPublicKey())
                ->where('private_key', $authToken->getPrivateKey())
                ->first();

    if($res == null) {
      return null;
    }

    return $authToken;
  }