Do I need caching in my node.js app

I am making a simple app in node.js and socket.io. The thing I am aiming for is response speed. User types and on each keypress gets results FAST. Number of records in the database: about 100k to start with. The records will be rarely changing.

Its setup like : receive data from browser via socket.io , do a sphinx search, do a mysql query. and send the data back to the browser via socket.emit. Simple!

Will this setup benefit from any kind of caching? I don't about the intricacies of caching but memcache/redis seem like an overkill.
Its just a hobby learning project btw