If you’re getting a 410 response it’s likely because you’re not sending the Accept: application/vnd.twitchtv.v5+json header. Kraken defaults to v3, which has now been removed, so unless you use that header to specify v5 you’ll just get that 410 error.
Also, Helix has the Get Broadcaster Subscriptions endpoint: https://dev.twitch.tv/docs/api/reference#get-broadcaster-subscriptions so if you have the appropriate scope from the channel you can see if a user is subscribed to them.