The property search keys of a record comes into picture when you are in the search page of a component or in a prompt dialogue page where you uses the record.

When you load a component, you can see some fields coming up to search for a value. These fields are the fields which are marked as the search keys for your search record. If you do not have any search key for your component, then you will be directly taken into thecomponent.

Read Further: http://peoplesoftiq.blogspot.com/2013/08/what-are-search-keys-in-re...