cabinet, wardrobe, closet, chest, coffer
櫝 centers on a wooden container for storing things: a cabinet, wardrobe, closet, chest, or coffer. All the given meanings are types of enclosed storage furniture or boxes.
櫝 combines 木 (tree, wood) with 賣, which likely contributes the sound. The character originally referred to a wooden box or cabinet.
The left side 木 (wood) tells you it's made of wood, and the right side 賣 looks like a complex container with shelves and a lid. Picture a wooden cabinet with many compartments for storing clothes and treasures.
For トク, imagine a wooden chest that is so special it feels like a 'toke' (token) of value: toke -> トク. The chest holds precious items.