They're a longtime hobby fish. You never see wild ones so they are often farm-bred.
Keyholes are peaceful, shy, and they don't really have much in the way of color. They range from grey to brown with black markings and white trim in the fins. Sometimes when excited (like during feeding or courting) they will show off a nice dark purple/blue iridescent sheen on their flanks, but unfortunately that comes and goes and they mostly stay brown. Males can top out around 6" but I have never seen one that large in person. Most end up between 3 - 5".
Mine did better when I kept them in larger tanks with peaceful but active tankmates. I had them with Uaru and small geos and they did well. When I tried to move them to a smaller 55 as a species tank, they constantly hid. I have the same experience with Crenicara punctulatum. They really need active, peaceful dithers to bring them out. Don't get anything too pushy or boisterous because that could make them skittish.
I always keep mine at 80 - 82F and give them weekly water changes. They aren't too fussy about water or food. Mine ate anything I fed, from small pellets and flakes to frozen and freeze-dried foods.
They're not the most colorful cichlid and a lot of people find them boring, but their chunky bodies and long fins give them a cute appearance, and they're a good choice for a quiet SA community setup.