Nextjs api route internal error in production

Question

All apis are working just fine when serving locally but when i try to deploy the app in vercel/ heroku, the apis give me internal error code 500.

So i tried to make a "test api " called hello, it worked just fine until i tried to open connection with db ( query was working locally but in production it gave me internal error)

Here is my code

const mysql= require("mysql2/promise")
export default async function hello(req, res) {
  const db= await mysql.createConnection({
    host:"eu-cdbr-west-02.cleardb.net",
    user:"########",
    password:"####",
    database:'####',
    port:'3306',
  })

  const [results] = await db.execute("select * from ##",[])
  db.end()
  res.json(results)
}

Update: On heroku, the api is taking 10 seconds to respond back