Welcome to the Community - No the VMs will not be affected by the migration as they are running on the ESXi host - The easiest way to switch databases is to back the database and restore to the new machine and created an ODBC connector to the new database - the new ODBC connector will have the SA credentials of the new SQL server -
I believe in the Upgrade Guide they five instructions on backing up the vCenter database and how to restore - or since it is a simple environment you might also just consider rebuilding the environment on the new vCenetr server