Authenticating users with JWT in Angular 4 + Node + MySQL - mysql

Question

I'm trying to do an auth login to an API request using JWT but I'm not being able to do it using my own database.
I'm using MySQL and, if you could, please provide me a code to do the response.
Until now I have only checked that if the email matches the one below ('mymail#domain), the user is authenticated.
I would like to know the best way to do a request to my MySQL database and compare the user with the one entered in the input, that all using JWT.
I'm learning so please, if you could explain the approach, I appreciate.
The frontend I'm using Angular 4, and this is the code:
login.component.html
<form class="form-signin" #f="ngForm" (ngSubmit)="signIn(f.value)">
<h2 class="form-signin-heading">Please sign in</h2>
<div *ngIf="invalidLogin" class="alert alert-danger">Invalid username and/or password.</div>
<label for="inputEmail" class="sr-only">Email address</label>
<input type="email" id="inputEmail" name="email" ngModel class="form-control" placeholder="Email address" required autofocus>
<label for="inputPassword" class="sr-only">Password</label>
<input type="password" id="inputPassword" name="password" ngModel class="form-control" placeholder="Password" required>
<button class="btn btn-lg btn-primary btn-block" type="submit">Sign in</button>
</form>
login.component.ts
import {Component, Inject} from '#angular/core';
import { Router } from "#angular/router";
import { AuthService } from '../../auth/auth.service';
...
email: string;
senha:string;
invalidLogin: boolean;
constructor(private router: Router,
private authService: AuthService) {}
signIn(credentials) {
this.authService.login(credentials)
.subscribe(result => {
if (result){
this.router.navigate(['/']);
}
else {
this.invalidLogin = true;
}
});
}
auth.service.ts
import { Http } from '#angular/http';
import { Injectable } from '#angular/core';
import { tokenNotExpired, JwtHelper } from 'angular2-jwt';
import 'rxjs/add/operator/map';
...
currentUser: any;
constructor(private http: Http) {
let token = localStorage.getItem('token');
if (token) {
let jwt = new JwtHelper();
this.currentUser = jwt.decodeToken(token);
}
}
login(credentials) {
return this.http.post('/api/user/authenticate', credentials)
.map(response => {
let result = response.json();
if (result && result.token) {
localStorage.setItem('token', result.token);
let jwt = new JwtHelper();
this.currentUser = jwt.decodeToken(localStorage.getItem('token'));
return true;
}
else return false;
});
}
This is my code in app.js (API in NodeJS)
const express = require('express');
const bodyParser = require('body-parser');
var jwt = require('jsonwebtoken');
var bcrypt = require('bcrypt');
...
app.post('/api/user/authenticate',function(req,res){
let body = req.body;
if (body.email === 'mymail#domain.com' && body.password === '1234') {
console.log('correct');
} else {
console.log('incorrect');
}
});
This is the endpoint where all my users are located:
/clientes
and it's shown like this:
{"ID":14,"Name":"Robert","Email":"robert#nest.com","Password":"14564964"}
Thank you!