Kenyan sand boas are small. Males require at least a 10 gallon, while females need at least 15. 20 or more is ideal, however. Get a reptile heating pad with a thermostat, and stick or slide it under one side of the terrarium. Cover the bottom of the enclosure with a repticarpet or something similar, this is to ensure the snake doesn't burn itself because of the heat pad. Glass gets hot! Then put a few inches of substrate in there. Never use sand, instead use aspen or carefresh. If you want to use something other than those, look it up to see if it is safe. Put a small and heavy water dish that isn't too deep on the cool side of the tank, and fill it with declorinated water every couple of days. You can have periods where it isn't filled to ensure the humidity doesn't get too high if you live somewhere humid. You could probably get away with having no hides, but try to put at least one in there. Clean the enclousure at least once a month, and always spot clean when you have to.
Feed your snake a mouse that is around the same size as the biggest part of its body. Baby sand boas eat pinkies (1-2 day old mice) and as they get older they can move on to fuzzies (10-13 day old mice) and eventually hopper mice. They don't outgrow mice, so you never have to move them over to rats.