What is the collective noun used for keys?

There isn't a widely accepted collective noun specifically for keys.

Here are some options you could use, depending on the context:

General:

* Set of keys

* Bunch of keys

* Collection of keys

More specific:

* Ring of keys (if they're on a key ring)

* Cluster of keys (if they're grouped together)

* Assortment of keys (if they're varied)

Ultimately, the best choice depends on the specific situation and the desired effect.