Most databases do have a way to force the index. See for example the MySQL way of doing it: https://dev.mysql.com/doc/refman/5.5/en/index-hints.html . You probably already know this but I mention it in case someone else does not.
Does that actually fail on an index missing? The docs for FORCE INDEX say "a table scan is used only if there is no way to use one of the named indexes to find rows in the table", which to me implies it's more like FORCEFULLY SUGGEST.
If your force index names a non-existent index, you'll get an error.