Key
Psychological (Freud)
Depth psychology reads the key as access to a chamber of the psyche that has stayed locked, a repressed secret or a possibility not yet lived. In the classical Freudian view the pairing of key and lock also carries a frankly erotic note of union.
Oriental reading
In Oriental and Islamic interpretation the key promises relief after hardship, the opening of closed doors, and the gaining of knowledge, office or provision. To be handed a key in a dream is often read as help in a difficult matter and success drawing near.
Objects
Dream interpretation is for self-reflection and entertainment — it is not a medical or psychological diagnosis.