Yes, it is safe for daily use. Your temps are still pretty low despite the 1.35 volts.
My general rule of thump is to keep the voltage below 1.35 and the average CPU temps under load to be below 80C. Heat is your main concern. Prolonged exposure to high temps is not good for a CPU. The more you increase the voltage, the more you increase the temps. So they work hand in hand. 60C temps for the CPU under load is very good.