handcuff vs keychain

handcuff

noun
  • One ring of a locking fetter for the hand or one pair. 

verb
  • To apply handcuffs to 

  • to restrain or restrict. 

keychain

noun
  • A chain or ring to which a key may be attached. 

  • An ornamental piece holding such a chain or ring. 

  • A digital repository for the storage of cryptographic keys. 

How often have the words handcuff and keychain occurred in a corpus of books? (source: Google Ngram Viewer )