On a site with very many files (many tens of thousands) noticed that a model call

$file = ee('Model')->get('File')->filter('file_name', $file_basename)->first();

was running unexpectedly slowly.

Upon investigation it turns out exp_files is only indexed on the upload_location_id and site_id

Have added some work-around code to compensate, but seems likely that many people will want to search for files by file_name ... so maybe would be helpful if this column was also indexed.