How to have a covering index used for the updates?

I have a db table with" - id bigint NOT NULL AUTO_INCREMENT (primary key) - customer_ref varchar(64) NOT NULL - customer_counter int NOT NULL - description varchar(255) NOT NULL I have also the following indexes: - PRIMARY KEY(id) - UNIQUE KEY c_ref (customer_ref) - KEY c_c (customer_counter) - KEY c_desc(customer_ref, description, customer_counter) I have the following update statements: UPDATE CustomerReferences SET customer_counter=100, description='invalidate due to X123' WHERE customer_ref='1000001' and description 'immutable' UPDATE CustomerReferences SET customer_counter=100, description='invalidate due to X123' WHERE id=2 and description 'immutable' Problem: I am using the EXPLAIN and I can't find a way to make the query filter the rows directly from the index. It always uses the index of the primary key or the unique key (c_ref). How can I index the table so that these updates filter/update directly via the index? Note that the particular updates should be no-ops as if I do select count(*) based on the where statement I get 0 rows due to the condition description 'immutable'