How to specify environment to point Cypress tests at the correct DB credentials?

Question

Below is the index.js code I am using to connect to a MySQL DB in my cypress test:

const mysql = require('mysql')
function queryTestDb(query, config) {
  const connection = mysql.createConnection(config.env.db)
  connection.connect()
  return new Promise((resolve, reject) => {
    connection.query(query, (error, results) => {
      if (error) reject(error)
      else {
        connection.end()
        return resolve(results)
      }
    })
  })
}

module.exports = (on, config) => {
  on('task', { queryDb: query => { return queryTestDb(query, config) }, });

  require('cypress-grep/src/plugin')(config)
  return config
}

Currently, my test use the DB credentials provided in cypress.json on this line:

  const connection = mysql.createConnection(config.env.db)

But I want the framework to run in different environments, as the database name is different.

I have already created qa.json & staging.json config files that store the DB credentials like so:

qa.json:

{
    "extends": "./cypress.json",
    "baseUrl": "myUrl",
    "env": {
        "db": {
          "host": "myHost",
          "user": "myUser",
          "password": "myPassword",
          "database": "taltektc_qa"
        }
      }
}

staging.json:

{
    "extends": "./cypress.json",
    "baseUrl": "myUrl",
    "env": {
        "db": {
          "host": "myUrl",
          "user": "myUser",
          "password": "myPassword",
          "database": "taltektc_stage"
        }
      }
}

Here is the command I am currently using to run the tests:

npx cypress open --config-file staging.json

I tried to update my index.js below, but I get a Cypress is not defined error message:

module.exports = (on, config) => {
    on('task', { queryDb: query => { return queryTestDb(query, Cypress.config()) }, });

Can someone please tell me what changes are required in my index.js so that I can specify which config file to use when making the DB connection?