SELECT 
  COUNT(*) 
FROM 
  cscart_categories 
WHERE 
  category_id = 250 
  AND storefront_id IN (0, 1)

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}

Result

COUNT(*)
0