One possible solution is to use Redis (REmote DIctionary Server). Redis is a very fast, powerful and stable keystore that is used in many projects . Stackoverflow also uses redis;).
I recently started using redis in my current project to create custom ratings. My personal opinion: redis is very simple, very fast and stable. He also has a nice command line client, I like it.
On the website, I am using the redis synchronous package. The server uses a twisted one and requires an asynchronous approach. Fortunately, there is a third-party txredis module that makes it easy to interact with a redis database using a twisted one. I had no problems with this. However, txredis does not have a connection pool, but it is not a problem to implement it manually if necessary.