The below advanced filter should accomplish your needs with some minor adjustments.

Simply replace PLAN_ID_HERE with the actual ID of your plan and place this within your Advanced Filter section of your list. This should filter out users with an active subscription to the above plan. Alternatively you could update a field value using CBSubs Fields or CBSubs SQL Actions on plan activation then filter based off that field however you'd need to manually fix existing users, the above works regardless as is direct query and requires no additional field.

I believe there is also a use case in the manual describing a different approach to set a CB field value when subscription starts and filter off of it.

Sorry, I don't mean to hijack the thread - but does this mean that we can have a list that would display only those members that are current in a specific plan (and not show them if they are expired/unpaid?)

Yes, that's exactly what the provided advanced filter does; it may require tweaks however depending on your needs and plan ids.