There are various small plastic sleeves that are archival quality without harmful chemicals that might destroy the card that will keep the card from getting any worse. DO NOT attempt to peel the lamination or it may totally destroy the card.

I've been working with various suppliers to find a good source of supply for sleeves that would be the right size for slot cards and room keys. I've seen several come in from foreign collectors in Europe that actually have a small flap that seals the card in the sleeve. I had one manufacturer in China that had something similar but shipping and minimum orders were pretty prohibitive. If anyone knows of a reasonable source please let me know.