SELECT 
  bundle_id 
FROM 
  cscart_product_bundle_product_links 
WHERE 
  product_id = 120593 
LIMIT 
  1

Query time 0.00016

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_product_bundle_product_links ref PRIMARY PRIMARY 3 const 1 Using index

Result

bundle_id
2070