keylogger still possible ?

can someone install an undetectable keylogger....if they had physical access to a computer....all while having Avast and Anti-Malware bytes already installed ?

If so, how to detect and remove?

Certain friends seem to vaguely mention specific sites and references I make when posting places....that are very unique, and that only I would know.

Gotta love this age of the internet, where you can't trust anyone...and everyones a little 007 weirdo.