Salted nuts might be useful. If they taste too salty to you, try buying both salted and unsalted of the same kind of nut, and mixing them thoroughly in the bag. Also, some trail mixes have salted nuts in with the fruit and such. Also, roasted nuts keep pretty well: if you want peanuts (say) today but not tomorrow, save them and maybe you'll want them again in a week or three.

Since you like sushi, have you tried packaged nori snacks? The energy requirement there that they might not be available in a non-Asian supermarket, but once you have them it's just open the package and eat.