Is crt_date an indexed column in the CST_INV_TRANSACTIONS table?

Is crt_date an indexed column in the CST_INV_TRANSACTIONS table? We want to rely on this column for the latest transaction in the system hence the question.

We have an extension that updates standard cost based on BPA cost changes and Work Order completion. This started as an issue with the cost transactions not inserting date in the table based on the primary key sequence so we switch to use crt_date but have concern we will have similar issue in future if this data is not indexed. Thanks, John