SELECT 
  product_id 
FROM 
  cscart_label_manager_product_artists 
WHERE 
  artist_id = 7491

Query time 0.00017

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_label_manager_product_artists ref artist_id artist_id 3 const 4

Result

product_id
42627
44891
44885
42310