I’ve sent a request to Developer Support as ticket # 14947692 to allow a maximum index of 3 (allowing 2 sets for key rotation in our production and testing environments).
Update (17 August 2022): Just to set timing expectations, this request from 27 July 2022 is still awaiting approval. If your application release schedule is dependent on this functionality, you might need to explore alternatives that allow you to ship sooner. The first ticket answer I received on 5 August 2022 suggested creating multiple applications, and I had to specifically draw attention again to the index parameter offer described in this thread, so this approval might be tied to the Zoom API release schedule.