How is the user's session properly checked?

Question

PHP

Good time, dear toaster!
Sessions are on my cookies, when registering, a user is created in the mysql database, with a hash, salt and a session that is created like this: md5(user_id + mail + salt) , the user is assigned in cookies:
User_id - record id from the
Session database - actually the md5 string ( user_id + mail + salt)
Question:
When navigating through the pages, you need to check whether the user has valid data and therefore access the database. I don’t want to load it once again, how to do it the right way? Can make a hash that can be verified without a db? (ala user_id+public_key (hanging in cookies) +private_key (known only to the server to authenticate the first two keys). Is it safe to do this? How do you do it?

Answer 1

1. You still need to make 5 - 10 - 100 requests to the database to assemble the page.
Another extra request does not play a role at all.
2. If the project is very loaded, it is quite appropriate to move the storage of these tokens to some redis.