Validating user token from backend

I am trying to verify on my backend side (node.js) user's token. Based on the official documentation docs I should download first all JWT from

https://cognito-idp.${region}.amazonaws.com/${UserPoolId}/.well-known/jwks.json

But for some reason this address doesn't exists (of course with valid region and UserPoolId). Everything should be configured well because signup, it's confirmation and login works perfectly, users are added to the pool, I've got token. Any idea what can be wrong ?

via Piotr Wójcik