I'm using Cache SQL and want the ability to choose a specific index.
I've boiled the problem down to one table and simplified the query down to
SELECT *
FROM Registration.PatResp
WHERE SchedApptNum=8450022
SchedApptNum is indexed, but instead of using that column, "Show Plan" indicates that it's looping through the entire Registration.PatResp table on Id (the primary key for the table).
I've done a tune-table with no change.