Is it possilbe for a 23 year old to have a heart attack?

Yes: Heart attacks represent sudden occlusion of a coronary artery. This happens most commonly because of atherosclerotic plaque rupture, although other things (like coronary spasm, Cocaine use, vasculitis etc) need to be considered, particularly in a 23 year old. Traditional risk factors might be less applicable.

Very very rare: Too young unless there are risk factors such as family and high cholesterol and others.