Zotero should have a Record Number column
Like in EndNote, a record number is efficient for people who want to create an index for their bibliography. I think it is simple to do that: just a code to enumerate all the entries and show the number in a column like the Creator, Year, etc.
If you put your keys in Extra like this:
Citation Key: Jones2013
Then they will migrate to the proper field once it’s added.
If you install the BetterBibTeX plugin, it can display citation keys as a column in the center pane