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 (
    30766, 30767, 30769, 30770, 30771, 30772, 
    30773, 30774, 30775, 30776, 30777, 
    30778, 30779, 30781, 30782, 30783, 
    30784, 30785, 30786, 30787, 30788, 
    30789, 30790, 30791, 30792, 30793, 
    30794, 30795, 30796, 30797, 30798, 
    30799
  ) 
GROUP BY 
  q_products_categories.product_id

Query time 0.00093

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "136.01"
    },
    "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": 40,
            "rows_produced_per_join": 40,
            "filtered": "100.00",
            "index_condition": "(`portal`.`q_products_categories`.`product_id` in (30766,30767,30769,30770,30771,30772,30773,30774,30775,30776,30777,30778,30779,30781,30782,30783,30784,30785,30786,30787,30788,30789,30790,30791,30792,30793,30794,30795,30796,30797,30798,30799))",
            "cost_info": {
              "read_cost": "80.01",
              "eval_cost": "8.00",
              "prefix_cost": "88.01",
              "data_read_per_join": "640"
            },
            "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": "40.00",
              "eval_cost": "1.60",
              "prefix_cost": "136.01",
              "data_read_per_join": "21K"
            },
            "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')))"
          }
        }
      ]
    }
  }
}