SELECT 
  q_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      q_products_categories.link_type = "M", 
      CONCAT(
        q_products_categories.category_id, 
        "M"
      ), 
      q_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  q_products_categories 
  INNER JOIN q_categories ON q_categories.category_id = q_products_categories.category_id 
  AND (
    q_categories.usergroup_ids = '' 
    OR FIND_IN_SET(0, q_categories.usergroup_ids) 
    OR FIND_IN_SET(1, q_categories.usergroup_ids)
  ) 
  AND q_categories.status IN ('A', 'H') 
WHERE 
  q_products_categories.product_id IN (
    32881, 32882, 32883, 32884, 32885, 32886, 
    32887, 32888, 32889, 32890, 32891, 
    10533, 10532, 10531, 10530, 10529, 
    10524, 10521, 8380, 8381, 8383, 8384, 
    8385, 8386, 8387, 8388, 8389, 8390, 
    8391, 8392, 8393, 8394
  ) 
GROUP BY 
  q_products_categories.product_id

Query time 0.00081

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "141.21"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "q_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 42,
            "rows_produced_per_join": 42,
            "filtered": "100.00",
            "index_condition": "(`portal`.`q_products_categories`.`product_id` in (32881,32882,32883,32884,32885,32886,32887,32888,32889,32890,32891,10533,10532,10531,10530,10529,10524,10521,8380,8381,8383,8384,8385,8386,8387,8388,8389,8390,8391,8392,8393,8394))",
            "cost_info": {
              "read_cost": "82.41",
              "eval_cost": "8.40",
              "prefix_cost": "90.81",
              "data_read_per_join": "672"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "q_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.q_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 8,
            "filtered": "20.00",
            "cost_info": {
              "read_cost": "42.00",
              "eval_cost": "1.68",
              "prefix_cost": "141.21",
              "data_read_per_join": "22K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "(((`portal`.`q_categories`.`usergroup_ids` = '') or find_in_set(0,`portal`.`q_categories`.`usergroup_ids`) or find_in_set(1,`portal`.`q_categories`.`usergroup_ids`)) and (`portal`.`q_categories`.`status` in ('A','H')))"
          }
        }
      ]
    }
  }
}