keyholder

noun3

1. •
   One who or a device or component which holds a key for security reasons.
2. •
   An individual or organization with access to a cryptographic key.

   • A key duplicating machine comprising […] a keyholder attached to said shaft, said keyholder providing for holding a key blank and an existing key having notches thereon; […] — 1978
3. •
   A dominant partner who holds the key to the chastity cage or belt of their submissive partner, or who otherwise controls whether they are able or allowed to receive orgasms or sexual stimulation.