From 2010, specialized FTP indexers existed. Some have been archived:
Be specific: "I’m looking for any historical index of a directory named 'crook' from around 2010, for digital archaeology purposes." index of crook 2010
Using open directories found via "index of" searches carries significant risks: From 2010, specialized FTP indexers existed
The phrase "index of crook 2010" most likely refers to the Crook: It's Good to Be Bad index of crook 2010