SELECT 
  cscart_promotions.*, 
  cscart_promotion_descriptions.name, 
  cscart_promotion_descriptions.detailed_description, 
  cscart_promotion_descriptions.short_description 
FROM 
  cscart_promotions 
  LEFT JOIN cscart_promotion_descriptions ON cscart_promotion_descriptions.promotion_id = cscart_promotions.promotion_id 
  AND cscart_promotion_descriptions.lang_code = 'en' 
  INNER JOIN cscart_ult_objects_sharing ON (
    cscart_ult_objects_sharing.share_object_id = cscart_promotions.promotion_id 
    AND cscart_ult_objects_sharing.share_company_id = 1 
    AND cscart_ult_objects_sharing.share_object_type = 'promotions'
  ) 
WHERE 
  1 
  AND IF(
    from_date, from_date <= 1781297984, 
    1
  ) 
  AND IF(to_date, to_date >= 1781297984, 1) 
  AND status IN ('A', 'H') 
  AND cscart_promotions.zone = 'catalog' 
ORDER BY 
  cscart_promotions.priority asc

Query time 0.00136

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_promotions.priority",
        "table": {
          "table_name": "cscart_promotions",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "rows": 1973,
          "filtered": 100,
          "attached_condition": "if(cscart_promotions.from_date,cscart_promotions.from_date <= 1781297984,1) and if(cscart_promotions.to_date,cscart_promotions.to_date >= 1781297984,1) and cscart_promotions.`status` in ('A','H') and cscart_promotions.zone = 'catalog'"
        }
      }
    },
    "table": {
      "table_name": "cscart_promotion_descriptions",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["promotion_id", "lang_code"],
      "ref": ["cscart_migrate.cscart_promotions.promotion_id", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_promotion_descriptions.lang_code = 'en')"
    },
    "table": {
      "table_name": "cscart_ult_objects_sharing",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "159",
      "used_key_parts": [
        "share_object_id",
        "share_company_id",
        "share_object_type"
      ],
      "ref": ["cscart_migrate.cscart_promotions.promotion_id", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "cscart_ult_objects_sharing.share_object_id = cscart_promotions.promotion_id and cscart_ult_objects_sharing.share_object_type = 'promotions'",
      "using_index": true
    }
  }
}

Result