How long does herpes virus live on finger if you touch a cold sore and dont wash your hands? is it a few seconds? or longer?

There is little or no risk of transmission, even immediately. Don't worry about infecting yourself at a new site; that almost never happens -- the immune system prevents new infections with the HSV type someone already has. In theory, there could be risk to a sex partner, e.g. if that finger then had contact with a partner's genital area. But nobody is known to have caught herpes from fingering.