If you have the box to add some SQL then I think you can try to add some impossible-to-get criteria in there and see how you get on.
It’s not really what it’s intended for, but it might work out for what you need.
Maybe something like:
SELECT id user_id, created_at granted_at
FROM users
WHERE id = -1000
Make sure auto-revoke isn’t set as well, as that would strip the manually granted ones too.