SELECT 
  cscart_pages.*, 
  cscart_page_descriptions.*, 
  cscart_seo_names.name as seo_name, 
  cscart_seo_names.path as seo_path 
FROM 
  cscart_pages 
  INNER JOIN cscart_page_descriptions ON cscart_pages.page_id = cscart_page_descriptions.page_id 
  LEFT JOIN cscart_seo_names ON cscart_seo_names.object_id = cscart_pages.page_id 
  AND cscart_seo_names.type = 'a' 
  AND cscart_seo_names.dispatch = '' 
  AND cscart_seo_names.lang_code = 'ru' 
WHERE 
  cscart_pages.page_id = 21 
  AND cscart_page_descriptions.lang_code = 'en' 
  AND (
    cscart_pages.usergroup_ids = '' 
    OR FIND_IN_SET(0, cscart_pages.usergroup_ids) 
    OR FIND_IN_SET(1, cscart_pages.usergroup_ids)
  ) 
  AND cscart_pages.page_type IN ('T', 'L', 'B', 'F')

Query time 0.00106

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.20"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_pages",
          "access_type": "const",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "page_id"
          ],
          "key_length": "3",
          "ref": [
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "2K"
          },
          "used_columns": [
            "page_id",
            "company_id",
            "parent_id",
            "id_path",
            "status",
            "page_type",
            "position",
            "timestamp",
            "usergroup_ids",
            "localization",
            "new_window",
            "use_avail_period",
            "avail_from_timestamp",
            "avail_till_timestamp",
            "facebook_obj_type",
            "abt__ut2_microdata_schema_type"
          ]
        }
      },
      {
        "table": {
          "table_name": "cscart_page_descriptions",
          "access_type": "const",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "page_id",
            "lang_code"
          ],
          "key_length": "9",
          "ref": [
            "const",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.20",
            "prefix_cost": "0.00",
            "data_read_per_join": "3K"
          },
          "used_columns": [
            "page_id",
            "lang_code",
            "page",
            "description",
            "meta_keywords",
            "meta_description",
            "page_title",
            "link"
          ]
        }
      },
      {
        "table": {
          "table_name": "cscart_seo_names",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "dispatch"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "object_id",
            "type",
            "dispatch",
            "lang_code"
          ],
          "key_length": "206",
          "ref": [
            "const",
            "const",
            "const",
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "1.00",
            "eval_cost": "0.20",
            "prefix_cost": "1.20",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "name",
            "object_id",
            "type",
            "dispatch",
            "path",
            "lang_code"
          ]
        }
      }
    ]
  }
}