SELECT 
  COUNT(*) 
FROM 
  cscart_categories 
WHERE 
  category_id = 166 
  AND company_id = 1 
  AND storefront_id IN (0, 1)

Query time 0.00025

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_categories const PRIMARY,p_category_id PRIMARY 3 const 1

Result

COUNT(*)
1