How to get the sites and BUs for Supplier business classification certificates?

Summary:

How to get the sites and BUs for Supplier business classification certificates?

The supplier business classification certificate is added at Profile level. We have a scenario to derive the supplier sites for some expired certificates based on some specific Country (BU) for which the certificate is associated.
Eg.
Supplier 'Test'
Sites
Site1 - London BU
Site2 - New York BU

Certificate A is applied to 'Test' supplier at profile level. Which means both Site1 and Site2 are associated to it by default.
Certificate A is expired and this certificate is specific to London as per business.

We need a query to derive only the Site1 (London BU) in above scenario and not Site2 (New York BU).