The key to build muscle mass is the resistance training program you use. Carbs are not really that important - it's a combination of the damage done by the resistance training and protein consumed that really drives muscle growth. What you use carbs for in this context is to replenish glycogen stores for the purposes of an energy boost in lifting.
Most ketogenic diets won't have you consuming enough protein to help with muscle growth, indeed, while I was training and low carb, I was far from low protein, consuming 200g per day of protein. Keeping Ketogenic at that stage is very difficult.
You can check out ketogenic bodybuilding sites, but it is much harder if you remain in that state.