const tokenKey = db.options.namespace.concat('-access-token:', req.user.token.id);
 const consumerTokensKey = db.options.namespace.concat('-consumer-access-tokens:', req.user.token.consumerId);
 db.multi()
     .hmset(tokenKey, req.user.token)
     .hset(consumerTokensKey, req.user.token.id, req.user.token.expiresAt)
     .exec();