List auth keys with created_at filter

I’d like to be able to list all auth keys (from plugin key-auth) that are older than a certain timestamp, to be able to remove them.
(in fact, if there was a way to tell Kong that a key expired at a specific date and time, it would even be easier, but I don’t believe that exists.)
Is there a way to do that?
I’ve tried to list the keys from a certain timestamp to first understand how the listing endpoint worked, and with:
curl -X GET
I get: {“message”:“An unexpected error occurred”}. The reason is:
2018/11/19 17:25:05 [error] 10702#0: *2501034 [lua] responses.lua:121: handler(): could not prepare query: [Invalid] Predicates on non-primary-key columns (created_at) are not yet supported for non secondary index queries, client:, server: kong_admin, request: “GET /key-auths?created_at=1540565503812 HTTP/1.1”, host: “”
So it appears that queries about created_at are not allowed (the message sent back to the api could probably be descriptive, but that’s not my point).
So, is there a way to do what I want? Or should I list every keys, and filter them on my end before calling the DELETE query?