How to optimize database query on opencart?

Question

MySQL

Good afternoon!
There is an opencart site, version 2.3, which has a product database of more than 200t and will expand to 500t
. At the moment, the database is already well optimized, but with each increase in the product it becomes slower and slower. It happens that when you go to a page, you wait until the page is loaded and eventually knocks out an error. There are two large queries that are normally tuned and optimized and tuned. But the problem remains that the more items, the slower it gets. The site itself is on a VPS.
Could you tell me which way to look, what you can read, which way to look?
PS: please do not write, like go to another better CMS, or change the platform, etc.
The issue needs to be resolved on opencart.
Thanks in advance to whoever answers

Answer 1

You write that everything is well optimized. And then you write that with such a small base you have brakes. Doesn't fit.
It is possible that there are simply not enough resources for the database, it may be configured incorrectly, queries may be optimized, but indexes are not optimized - superfluous or missing. You should profile requests, and only then look for the causes.