express login auth jwt

auth.js

login(req, res) {
        if (!req.body.memail || !req.body.mpassword) {
            return res.status(404).send({
            message: 'Email and password can not be empty!',
            });
        } else {
            const email = req.body.memail;
            const password = crypto.createHash('md5').update(req.body.mpassword).digest("hex");
            const potentialUser = {
                where: {
                    memail: email,
                    mpassword: password
                },
                attributes: ['memail', 'muuid', 'cid']
            };
            Member.findOne(potentialUser)
            .then(user => {
                if(!user) {
                    return res.status(404).send({
                         message: 'fail',
                         error: 'User not found. Authentication failed.'
                     });
                }
                const token = jwt.sign({
                    muuid: user.muuid,
                    memail: user.memail,
                    cid: user.cid
                }, 
                'secret_key',
                {
                    expiresIn :"2h"
                }
                )
                return res.status(200).send({ message: 'success', token: token});

            })
            .catch((error) => res.status(400).send(error));
        }
    }