SELECT 
  cscart_discussion_posts.*, 
  cscart_discussion_messages.message, 
  cscart_discussion_rating.rating_value, 
  cscart_cp_pr_reviews_reply.cp_admin_answ, 
  cscart_cp_pr_reviews_reply.cp_admin_answ_time, 
  cscart_cp_pr_reviews_reply.cp_admin_id, 
  cscart_cp_pr_reviews_reply.reason, 
  cscart_cp_pr_reviews_reply.status as reply_status, 
  cscart_discussion_messages.cp_pr_title, 
  cscart_discussion_messages.cp_pr_advantages, 
  cscart_discussion_messages.cp_pr_disadvantages, 
  cscart_users.user_type 
FROM 
  cscart_discussion_posts 
  LEFT JOIN cscart_discussion_messages ON cscart_discussion_messages.post_id = cscart_discussion_posts.post_id 
  LEFT JOIN cscart_discussion_rating ON cscart_discussion_rating.post_id = cscart_discussion_posts.post_id 
  LEFT JOIN cscart_cp_pr_reviews_reply ON cscart_cp_pr_reviews_reply.post_id = cscart_discussion_posts.post_id 
  LEFT JOIN cscart_users ON cscart_users.user_id = cscart_discussion_posts.user_id 
WHERE 
  cscart_discussion_posts.thread_id = 7683 
  AND cscart_discussion_posts.status = 'A' 
  AND cscart_discussion_posts.cp_pr_user_delete = 'N' 
ORDER BY 
  cscart_discussion_posts.timestamp DESC 
LIMIT 
  0, 10

Query time 0.00071

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "read_sorted_file": {
          "filesort": {
            "sort_key": "cscart_discussion_posts.`timestamp` desc",
            "table": {
              "table_name": "cscart_discussion_posts",
              "access_type": "ref",
              "possible_keys": ["thread_id", "thread_id_2"],
              "key": "thread_id_2",
              "key_length": "6",
              "used_key_parts": ["thread_id", "status"],
              "ref": ["const", "const"],
              "rows": 3,
              "filtered": 100,
              "index_condition": "cscart_discussion_posts.`status` = 'A'",
              "attached_condition": "cscart_discussion_posts.thread_id <=> 7683 and cscart_discussion_posts.`status` <=> 'A' and cscart_discussion_posts.cp_pr_user_delete = 'N'"
            }
          }
        }
      },
      {
        "table": {
          "table_name": "cscart_discussion_messages",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["post_id"],
          "ref": ["lillyshop_lillyshop.cscart_discussion_posts.post_id"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "cscart_discussion_rating",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["post_id"],
          "ref": ["lillyshop_lillyshop.cscart_discussion_posts.post_id"],
          "rows": 1,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "cscart_cp_pr_reviews_reply",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["post_id"],
          "ref": ["lillyshop_lillyshop.cscart_discussion_posts.post_id"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(cscart_cp_pr_reviews_reply.post_id = cscart_discussion_posts.post_id)"
        }
      },
      {
        "table": {
          "table_name": "cscart_users",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["user_id"],
          "ref": ["lillyshop_lillyshop.cscart_discussion_posts.user_id"],
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}