You can use IZArc's searching tool to find files in archives. To activate this tool, select Find in Archives from the Tools menu.
You have to select a folder when the archives you want to search in are, enter the file name you looking for (you can use wildcards separated with comma or semi-colon - for example: *.txt; *.jpg; *.exe), also you can filter the archives by type and may choose to search in folders recursive.
Then click on "Search" button to start searching.
After the search is finished you can open a file from the list by double-clicking on the selected file.