Is it possible to limit routing to only activities that have particular custom property set?

Summary:

We have a change in our business model where for some activity types we only assign to a worker if the customer has paid and I am looking at how to achieve this in routing.

Content (required):

We have are wanting to continue to use the current process we have which finds availability using the Booking Options API and then creates an activity via the API, with routing running every 5 minutes to allocate the appointment to a staff member, but want to only include activities that have a payment status of PAID (custom property).

Is this possible?

Version (include the version you are using, if applicable):