There are a few optical storage mediums designed for long term archival storage. Like M-Disc or (as mentioned in the article) pioneers DM for Archive, both of which are still commercially available.

And provided they're stored properly, even more general consumer oriented optical media can easily last a few decades. Granted the environmental aspect of "proper storage" (<50% relative humidity, constant temp <80F and >50F) can be difficult to achieve at home in a lot of regions, but generally banks and credit unions have an option to get a safety deposit box which is generally in an environmentally controlled room. Other than that just store your media in an opaque single disc case.