If I press CTRL+F to search for a specific text then I get this result:
The contrast is extremly bad and I can't read it. I searched the whole menu but can't find out how I can change the color for this.
Where can I change the color for search results?
You must be using some custom or non-standard color schema .. because standard ones (Default + Darcula at very least) have them set pretty visible.
Using search box in Settings/Preferences with search
as text narrows possible options to few places.
In any case:
Settings/Preferences
Editor | Colors & Fonts
General --> Search Results | Text search result