Scorching the inside is usually a precautionary step for those times for boxes are in the barn for the past 20 years (Old timer stored, died, getting out of bees, etc.), and the history is unknown.
For a three year old TBH, I'll assume you know whom you bought the equipment from, the history of past problems, etc. I would not think that a three year old TBH would have many problems.
If this is your equipment, no scorching is needed....unless you had AFB.
Scorching is for disease control, and nothing else.