You're running up against built-in functionality: once the "unlock" screen appears and you don't enter your password, macOS falls back on the screen saver, or (without a screen saver) goes off. Or, as you've noticed, when you use cmd+ctrl+q, it just goes to sleep, screen saver or no. There's no control to change that behavior in the OS.
However, there are some free utilities on the Internet and the App store (Caffeine and Anti Sleep come to mind, but there are others) which disable the display sleep and/or the system sleep. I gave Anti Sleep a try with the keyboard shortcut, and it did just what you're looking to accomplish: it kept the screen "awake" after it was locked.
Edit: It looks like cmd+ctrl+q and Anti-Sleep's first option, "Prevent System Sleep when lid is closed" don't play together too well. Uncheck that option to make this work.
All that said, be aware that the sleep feature is built-in to reduce power consumption and extend the life of your display. By leaving the screen powered on all the time, you negate these protections.