SELECT 
  COUNT(*) 
FROM 
  cscart_promotions 
  LEFT JOIN cscart_promotion_descriptions ON cscart_promotion_descriptions.promotion_id = cscart_promotions.promotion_id 
  AND cscart_promotion_descriptions.lang_code = 'ru' 
  LEFT JOIN cscart_storefronts_promotions AS storefronts_promotions ON storefronts_promotions.promotion_id = cscart_promotions.promotion_id 
  LEFT JOIN cscart_promotion_images ON cscart_promotion_images.promotion_id = cscart_promotions.promotion_id 
  AND cscart_promotion_images.lang_code = 'ru' 
WHERE 
  1 
  AND IF(
    from_date, from_date <= 1785181440, 
    1
  ) 
  AND IF(to_date, to_date >= 1785181440, 1) 
  AND status IN ('A') 
  AND (
    storefronts_promotions.storefront_id = 1 
    OR storefronts_promotions.storefront_id IS NULL
  )

Query time 0.00108

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "5.64"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_promotions",
          "access_type": "ALL",
          "rows_examined_per_scan": 7,
          "rows_produced_per_join": 0,
          "filtered": "14.29",
          "cost_info": {
            "read_cost": "1.24",
            "eval_cost": "0.10",
            "prefix_cost": "1.34",
            "data_read_per_join": "79"
          },
          "used_columns": [
            "promotion_id",
            "to_date",
            "from_date",
            "status"
          ],
          "attached_condition": "((0 <> if(`testdobroded`.`cscart_promotions`.`from_date`,(`testdobroded`.`cscart_promotions`.`from_date` <= 1785181440),1)) and (0 <> if(`testdobroded`.`cscart_promotions`.`to_date`,(`testdobroded`.`cscart_promotions`.`to_date` >= 1785181440),1)) and (`testdobroded`.`cscart_promotions`.`status` = 'A'))"
        }
      },
      {
        "table": {
          "table_name": "cscart_promotion_descriptions",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "promotion_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "testdobroded.cscart_promotions.promotion_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 0,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "0.25",
            "eval_cost": "0.10",
            "prefix_cost": "1.69",
            "data_read_per_join": "799"
          },
          "used_columns": [
            "promotion_id",
            "lang_code"
          ]
        }
      },
      {
        "table": {
          "table_name": "storefronts_promotions",
          "access_type": "index",
          "key": "PRIMARY",
          "used_key_parts": [
            "storefront_id",
            "promotion_id"
          ],
          "key_length": "8",
          "rows_examined_per_scan": 16,
          "rows_produced_per_join": 15,
          "filtered": "100.00",
          "using_index": true,
          "using_join_buffer": "hash join",
          "cost_info": {
            "read_cost": "0.51",
            "eval_cost": "1.60",
            "prefix_cost": "3.79",
            "data_read_per_join": "255"
          },
          "used_columns": [
            "storefront_id",
            "promotion_id"
          ],
          "attached_condition": "(<if>(found_match(storefronts_promotions), ((`testdobroded`.`storefronts_promotions`.`storefront_id` = 1) or (`testdobroded`.`storefronts_promotions`.`storefront_id` is null)), true) and <if>(is_not_null_compl(storefronts_promotions), (`testdobroded`.`storefronts_promotions`.`promotion_id` = `testdobroded`.`cscart_promotions`.`promotion_id`), true))"
        }
      },
      {
        "table": {
          "table_name": "cscart_promotion_images",
          "access_type": "eq_ref",
          "possible_keys": [
            "promo"
          ],
          "key": "promo",
          "used_key_parts": [
            "promotion_id",
            "lang_code"
          ],
          "key_length": "10",
          "ref": [
            "testdobroded.cscart_promotions.promotion_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 15,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "0.25",
            "eval_cost": "1.60",
            "prefix_cost": "5.64",
            "data_read_per_join": "255"
          },
          "used_columns": [
            "promotion_id",
            "lang_code"
          ],
          "attached_condition": "<if>(is_not_null_compl(cscart_promotion_images), (`testdobroded`.`cscart_promotion_images`.`promotion_id` = `testdobroded`.`cscart_promotions`.`promotion_id`), true)"
        }
      }
    ]
  }
}