According to Official Guinness Records,
The largest collection of keys belongs to Lisa J. Large (USA) and consists of 3,604 keys as of 20 November 2013, in Kansas City, Missouri, USA.
Lisa J. Large's goal was to break a Guinness World Records title before turning 30 years of age. Lisa already had a large collection of keys and decided to increase her collection to a record worthy size. It took her two years to collect and catalogue the collection. Two days before her 31st birthday, Lisa displayed her collection to be verified by members of the public and independent witnesses. The keys are kept in nine binders. Lisa's favourite key is number 3,604, it is the key to the first house she bought.
For a complete list of 2013 records, please visit 2013 Guinness Records in United States.