Any ideas on non-perishable foods I can put into my packed lunch?

I have to attend work training in a few days and I need to bring a packed lunch. The training detail says that there will be no time to buy lunch anywhere so packed lunch it is. The venue is a 2 hour train ride from my house and starts in the morning. Thus, I have to leave the house at 6am.

Normally if take a packed lunch into work/school, I can usually eat it within 4/5 hours and I have a tiny freezer pack that I use.

However, because of my departure time, and not knowing when lunch actually is I probably won’t eat the lunch for up to 7 hours. Usually by then my freezer pack has completely melted and I’m a little worried about the food.

What are some non-perishable foods that I can pack in my lunch that a) don’t need refrigeration and b) can be enough to fuel me for another 7 hours before I get home.

Any ideas on non-perishable foods I can put into my packed lunch?