SELECT 
  b.row 
FROM 
  (
    SELECT 
      product_id, 
      @r := @r + 1 as row 
    FROM 
      (
        SELECT 
          products.product_id 
        FROM 
          cscart_products as products 
          LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
          AND descr1.lang_code = 'en' 
          LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
          AND prices.lower_limit = 1 
          INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
          INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
          AND (
            cscart_categories.usergroup_ids = '' 
            OR FIND_IN_SET(
              0, cscart_categories.usergroup_ids
            ) 
            OR FIND_IN_SET(
              1, cscart_categories.usergroup_ids
            )
          ) 
          AND cscart_categories.status IN ('A', 'H') 
          LEFT JOIN cscart_ult_product_descriptions shared_descr ON shared_descr.product_id = products.product_id 
          AND shared_descr.company_id = 1 
          AND shared_descr.lang_code = 'en' 
          LEFT JOIN cscart_product_popularity as popularity ON popularity.product_id = products.product_id 
        WHERE 
          1 
          AND cscart_categories.category_id IN (1845) 
          AND cscart_categories.company_id = 1 
          AND (
            products.usergroup_ids = '' 
            OR FIND_IN_SET(0, products.usergroup_ids) 
            OR FIND_IN_SET(1, products.usergroup_ids)
          ) 
          AND products.status IN ('A') 
          AND prices.usergroup_id IN (0, 0, 1) 
        GROUP BY 
          products.product_id 
        ORDER BY 
          descr1.product asc
      ) AS a
  ) AS b 
WHERE 
  b.product_id = 65797

Query time 0.00060

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "<derived2>",
      "access_type": "ALL",
      "rows": 2,
      "filtered": 100,
      "attached_condition": "b.product_id = 65797",
      "materialized": {
        "query_block": {
          "select_id": 2,
          "table": {
            "table_name": "<derived3>",
            "access_type": "ALL",
            "rows": 2,
            "filtered": 100,
            "materialized": {
              "query_block": {
                "select_id": 3,
                "table": {
                  "message": "no matching row in const table"
                }
              }
            }
          }
        }
      }
    }
  }
}