Forgive my ignorance, but if you are going to all the trouble of storing the JWT id in a server side database for verification why don't you just store the JWTs' claims as well and just hand the client an opaque random id? Your gateway could do the lookup and supply the claims to your backend without the client knowing anything about it. You wouldn't even have to validate the claims, since they never leave your servers.

The best part of using JWTs is that you can validate without a central database. If you need a central database for sessions anyway you might as well store the claims in it.