SELECT 
  COUNT(
    DISTINCT(cscart_pages.page_id)
  ) 
FROM 
  cscart_pages 
  LEFT JOIN cscart_page_descriptions ON cscart_pages.page_id = cscart_page_descriptions.page_id 
  AND cscart_page_descriptions.lang_code = 'ja' 
  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 = 'ja' 
  INNER JOIN cscart_ult_objects_sharing ON (
    cscart_ult_objects_sharing.share_object_id = cscart_pages.page_id 
    AND cscart_ult_objects_sharing.share_company_id = 2 
    AND cscart_ult_objects_sharing.share_object_type = 'pages'
  ) 
WHERE 
  1 
  AND cscart_pages.parent_id IN (37) 
  AND cscart_pages.status IN ('A') 
  AND cscart_pages.page_type IN ('B') 
  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.use_avail_period = 'N' 
    OR (
      cscart_pages.use_avail_period = 'Y' 
      AND cscart_pages.avail_from_timestamp <= 1762128220 
      AND (
        cscart_pages.avail_till_timestamp >= 1762128220 
        OR cscart_pages.avail_till_timestamp = 0
      )
    )
  ) 
ORDER BY 
  cscart_pages.timestamp desc

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_pages",
      "access_type": "ref",
      "possible_keys": ["PRIMARY", "parent_id"],
      "key": "parent_id",
      "key_length": "3",
      "used_key_parts": ["parent_id"],
      "ref": ["const"],
      "rows": 7,
      "filtered": 100,
      "attached_condition": "cscart_pages.`status` = 'A' and cscart_pages.page_type = 'B' 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.use_avail_period = 'N' or cscart_pages.use_avail_period = 'Y' and cscart_pages.avail_from_timestamp <= 1762128220 and (cscart_pages.avail_till_timestamp >= 1762128220 or cscart_pages.avail_till_timestamp = 0))"
    },
    "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_purchase_fl_com.cscart_pages.page_id", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "cscart_ult_objects_sharing.share_object_id = cscart_pages.page_id and cscart_ult_objects_sharing.share_object_type = 'pages'",
      "using_index": true
    },
    "table": {
      "table_name": "cscart_seo_names",
      "access_type": "ref",
      "possible_keys": ["PRIMARY", "dispatch"],
      "key": "PRIMARY",
      "key_length": "206",
      "used_key_parts": ["object_id", "type", "dispatch", "lang_code"],
      "ref": [
        "cscart_purchase_fl_com.cscart_pages.page_id",
        "const",
        "const",
        "const"
      ],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_seo_names.`type` = 'a' and cscart_seo_names.dispatch = '' and cscart_seo_names.lang_code = 'ja')",
      "using_index": true
    }
  }
}