If the film is in its plastic canister, you've nothing to worry about. The box is going in the (recycle) dustbin anyway. Kodachrome here UK) is process paid, so I take the envelopes out of the boxes, discard the boxes except for the box end flaps, and put the film canisters in pairs in food bags, tied in a knot, then the canister bags go in sealed plastic tubs. When I need film, it's usually in pairs, so I open the plastic box, take out a pair, or if it's just one I need, put the other canister back in a bag and into the box.

These plastic canisters are pretty airtight, and I've never had a problem in decades of storing film like this.