SELECT 
  COUNT(*) 
FROM 
  jmj_promotions 
  LEFT JOIN jmj_promotion_descriptions ON jmj_promotion_descriptions.promotion_id = jmj_promotions.promotion_id 
  AND jmj_promotion_descriptions.lang_code = 'en' 
  LEFT JOIN jmj_storefronts_promotions AS storefronts_promotions ON storefronts_promotions.promotion_id = jmj_promotions.promotion_id 
  LEFT JOIN jmj_promotion_images ON jmj_promotion_images.promotion_id = jmj_promotions.promotion_id 
  AND jmj_promotion_images.lang_code = 'en' 
WHERE 
  1 
  AND status IN ('A') 
  AND (
    storefronts_promotions.storefront_id = 1 
    OR storefronts_promotions.storefront_id IS NULL
  ) 
  AND 1

Query time 0.00082

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.99"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "storefronts_promotions",
          "access_type": "system",
          "rows_examined_per_scan": 0,
          "rows_produced_per_join": 1,
          "filtered": "0.00",
          "const_row_not_found": true,
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "16"
          },
          "used_columns": [
            "storefront_id",
            "promotion_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "jmj_promotion_images",
          "access_type": "system",
          "possible_keys": [
            "promo"
          ],
          "rows_examined_per_scan": 0,
          "rows_produced_per_join": 1,
          "filtered": "0.00",
          "const_row_not_found": true,
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "16"
          },
          "used_columns": [
            "promotion_id",
            "lang_code"
          ]
        }
      },
      {
        "table": {
          "table_name": "jmj_promotions",
          "access_type": "ALL",
          "rows_examined_per_scan": 15,
          "rows_produced_per_join": 1,
          "filtered": "10.00",
          "cost_info": {
            "read_cost": "6.39",
            "eval_cost": "0.30",
            "prefix_cost": "6.69",
            "data_read_per_join": "120"
          },
          "used_columns": [
            "promotion_id",
            "status"
          ],
          "attached_condition": "(`jmj_test`.`jmj_promotions`.`status` = 'A')"
        }
      },
      {
        "table": {
          "table_name": "jmj_promotion_descriptions",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "promotion_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "jmj_test.jmj_promotions.promotion_id",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.30",
            "prefix_cost": "6.99",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "promotion_id",
            "lang_code"
          ]
        }
      }
    ]
  }
}