Questiion. Does expriry option gets reset when cache is served to the user? about express-redis-cache HOT 1 OPEN

it would be 30 seconds as I hope you expect, if you want your cache to last longer, simply set the expiration to a longer value.
If a page is requested every 30 seconds for a page that expire after 60 seconds and that library will change the expiration cache to 60 seconds after every request you will end up with a page that never renew.

Although there's an interesting thought here, there could be an option to set the cache in redis for ever along with the expiration time, when the expiration time is expired, the library could return the cache one last time and rebuild the cache in the background for the next requests.
Although it would not be a good idea to make that the default behavior, it could be an opt-in option. Similar to an http cache control stale-while-revalidate.

from express-redis-cache.