Moonsilver Key is a uncommon Artifact card from Innistrad: Midnight Hunt (MID), collector number 255. Current market price: $1.00 (foil $5.06), TCGplayer market prices via Scryfall.
{1}, {T}, Sacrifice this artifact: Search your library for an artifact card with a mana ability or a basic land card, reveal it, put it into your hand, then shuffle.