Here's the screenshot with more details:
https://imgur.com/a/disabling-touch-...tbooks-1534va9
Go to Settings > Personalize > Key Mapping > EPUB, FB2 and Others. Here you can map "Touch screen lock" action to Back button, and it's the only button which allows it. The name is a bit misleading, but with this setup I can disable the touch input with long press of the Back button.