SELECT 
  a.*, 
  b.description 
FROM 
  cscart_currencies as a 
  LEFT JOIN cscart_currency_descriptions as b ON a.currency_code = b.currency_code 
  AND lang_code = 'en' 
  INNER JOIN cscart_ult_objects_sharing ON (
    cscart_ult_objects_sharing.share_object_id = a.currency_id 
    AND cscart_ult_objects_sharing.share_company_id = 1 
    AND cscart_ult_objects_sharing.share_object_type = 'currencies'
  ) 
WHERE 
  1 
  AND status IN ('A', 'H') 
ORDER BY 
  a.position

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "a.position",
        "table": {
          "table_name": "a",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "rows": 3,
          "filtered": 100,
          "attached_condition": "a.`status` in ('A','H')"
        }
      }
    },
    "table": {
      "table_name": "b",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "38",
      "used_key_parts": ["currency_code", "lang_code"],
      "ref": ["rfswire_cart.a.currency_code", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(b.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": ["rfswire_cart.a.currency_id", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "cscart_ult_objects_sharing.share_object_id = a.currency_id and cscart_ult_objects_sharing.share_object_type = 'currencies'",
      "using_index": true
    }
  }
}