for keeps vs until the end of time

for keeps

prep
  • With an agreement or intention to retain what one gains or receives. 

  • Permanently, so that one can keep something indefinitely. 

  • With a strong competitive resolve to win or succeed, as in sports or business. 

until the end of time

How often have the words for keeps and until the end of time occurred in a corpus of books? (source: Google Ngram Viewer )