It only needs like 3-9 seconds to heat something that small hot enough to soften locktight. You don't dont need red hot either. I find a soft butane lighter mini torch flame to be very effective on slowly raising temp. A sharp flame tip tends to deflect on small heads and heats a background surface more...(paints?)
Stuck without heat, inducing shock might work; sharp taps.....
.....if the screwdriver tip doesn't shatter