I built an application for exactly this. It's called A Personal Search Engine, APSE for short.[0]
It OCRs screenshots and stores the text in a search index, so you can query by keyword, date, boolean operators, the whole shebang.
It's all local. It is really useful for me - yesterday it saved me after Firefox wigged out and lost all my tabs. It's in a great place to try out, and I am actively developing it.
[0] https://apse.io