SELECT 
  products.company_id as variant_id, 
  companies.company as variant 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  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_product_review_prepared_data ON cscart_product_review_prepared_data.product_id = products.product_id 
  AND cscart_product_review_prepared_data.storefront_id = 0 
WHERE 
  1 = 1 
  AND cscart_categories.category_id IN (66, 67, 68, 69, 70) 
  AND companies.status = 'A' 
  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 (
    NOT FIND_IN_SET(0, blacklist) 
    OR blacklist IS NULL
  ) 
  AND products.product_type != 'D' 
GROUP BY 
  products.company_id 
ORDER BY 
  companies.company ASC

Query time 0.00081

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "companies.company",
      "temporary_table": {
        "table": {
          "table_name": "cscart_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "p_category_id",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "rows": 5,
          "filtered": 100,
          "attached_condition": "cscart_categories.category_id in (66,67,68,69,70) 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')",
          "using_index": true
        },
        "table": {
          "table_name": "products_categories",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["vietpom_dev.cscart_categories.category_id"],
          "rows": 2,
          "filtered": 100,
          "using_index": true
        },
        "table": {
          "table_name": "products",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "status", "product_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["vietpom_dev.products_categories.product_id"],
          "rows": 1,
          "filtered": 81.30841064,
          "attached_condition": "(products.usergroup_ids = '' or find_in_set(0,products.usergroup_ids) or find_in_set(1,products.usergroup_ids)) and products.`status` = 'A' and (!find_in_set(0,products.blacklist) or products.blacklist is null) and products.product_type <> 'D'"
        },
        "block-nl-join": {
          "table": {
            "table_name": "companies",
            "access_type": "ALL",
            "possible_keys": ["PRIMARY"],
            "rows": 4,
            "filtered": 100,
            "attached_condition": "companies.`status` = 'A'"
          },
          "buffer_type": "flat",
          "buffer_size": "26Kb",
          "join_type": "BNL",
          "attached_condition": "companies.company_id = products.company_id"
        }
      }
    }
  }
}