SELECT 
  lang.name, 
  IF(
    cscart_ult_language_values.value IS NULL, 
    lang.value, cscart_ult_language_values.value
  ) as value 
FROM 
  cscart_language_values lang 
  LEFT JOIN cscart_ult_language_values ON cscart_ult_language_values.name = lang.name 
  AND company_id = 1 
  AND cscart_ult_language_values.lang_code = lang.lang_code 
WHERE 
  lang.lang_code = 'ru' 
  AND lang.name IN (
    'register_new_account', 'contact_information', 
    'text_multiprofile_wholesale_notice', 
    'text_multiprofile_notice', 'billing_address', 
    'shipping_address', 'shipping_address', 
    'billing_address', 'revert', 'delete_my_account_description', 
    'delete_my_account', 'delete_my_account', 
    'delete_my_account', 'usergroup', 
    'status', 'action', 'active', 'available', 
    'join', 'declined', 'join', 'pending', 
    'cancel', 'register_new_account', 
    'contact_information', 'text_multiprofile_wholesale_notice', 
    'text_multiprofile_notice', 'billing_address', 
    'shipping_address', 'shipping_address', 
    'billing_address', 'revert', 'delete_my_account_description', 
    'delete_my_account', 'delete_my_account', 
    'delete_my_account', 'usergroup', 
    'status', 'action', 'active', 'available', 
    'join', 'declined', 'join', 'pending', 
    'cancel'
  )

Query time 0.00096

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "18.91"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "lang",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "lang_code",
            "name"
          ],
          "key_length": "392",
          "rows_examined_per_scan": 18,
          "rows_produced_per_join": 18,
          "filtered": "100.00",
          "index_condition": "((`test_uchur_k`.`lang`.`lang_code` = 'ru') and (`test_uchur_k`.`lang`.`name` in ('register_new_account','contact_information','text_multiprofile_wholesale_notice','text_multiprofile_notice','billing_address','shipping_address','shipping_address','billing_address','revert','delete_my_account_description','delete_my_account','delete_my_account','delete_my_account','usergroup','status','action','active','available','join','declined','join','pending','cancel','register_new_account','contact_information','text_multiprofile_wholesale_notice','text_multiprofile_notice','billing_address','shipping_address','shipping_address','billing_address','revert','delete_my_account_description','delete_my_account','delete_my_account','delete_my_account','usergroup','status','action','active','available','join','declined','join','pending','cancel')))",
          "cost_info": {
            "read_cost": "10.81",
            "eval_cost": "1.80",
            "prefix_cost": "12.61",
            "data_read_per_join": "7K"
          },
          "used_columns": [
            "lang_code",
            "name",
            "value"
          ]
        }
      },
      {
        "table": {
          "table_name": "cscart_ult_language_values",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "lang_code",
            "name",
            "company_id"
          ],
          "key_length": "396",
          "ref": [
            "test_uchur_k.lang.lang_code",
            "test_uchur_k.lang.name",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 18,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "4.50",
            "eval_cost": "1.80",
            "prefix_cost": "18.91",
            "data_read_per_join": "7K"
          },
          "used_columns": [
            "lang_code",
            "name",
            "value",
            "company_id"
          ]
        }
      }
    ]
  }
}