SELECT 
  products.product_id 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_products_categories as products_categories ON products.product_id = products_categories.product_id 
WHERE 
  products.product_id = 28942 
  AND 1 
  AND products_categories.category_id IN (
    2974, 3070, 458, 277, 3078, 281, 3097, 
    3098, 3099, 290, 296, 2662, 508, 3100, 
    3101, 620, 782, 1186, 3039, 3055, 3107, 
    3106, 3102, 3103, 3104, 3105, 2978, 
    2913, 2215, 2661, 2488, 2656, 3114, 
    2438, 3094, 2645, 2659, 2663, 2658, 
    2654, 2453, 2643, 2644, 2653, 2651, 
    2652, 2463, 2640, 2649, 2650, 2473, 
    2646, 2648, 2684, 2660, 2642, 2647, 
    2641, 2494, 2655, 2657, 2664, 2666, 
    2665, 3093, 2667, 2668, 2669, 2670, 
    2671, 2672, 2673, 2674, 2675, 2676, 
    2677, 2678, 2679, 2680, 2681, 2682, 
    2683, 3020, 2973
  )

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.48"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "products",
          "access_type": "const",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "ref": [
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 1,
          "filtered": "100.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "0.00",
            "eval_cost": "0.10",
            "prefix_cost": "0.00",
            "data_read_per_join": "5K"
          },
          "used_columns": [
            "product_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "products_categories",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "pt"
          ],
          "key": "pt",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "ref": [
            "const"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 0,
          "filtered": "50.00",
          "using_index": true,
          "cost_info": {
            "read_cost": "0.38",
            "eval_cost": "0.05",
            "prefix_cost": "0.48",
            "data_read_per_join": "8"
          },
          "used_columns": [
            "product_id",
            "category_id"
          ],
          "attached_condition": "(`cscart_db`.`products_categories`.`category_id` in (2974,3070,458,277,3078,281,3097,3098,3099,290,296,2662,508,3100,3101,620,782,1186,3039,3055,3107,3106,3102,3103,3104,3105,2978,2913,2215,2661,2488,2656,3114,2438,3094,2645,2659,2663,2658,2654,2453,2643,2644,2653,2651,2652,2463,2640,2649,2650,2473,2646,2648,2684,2660,2642,2647,2641,2494,2655,2657,2664,2666,2665,3093,2667,2668,2669,2670,2671,2672,2673,2674,2675,2676,2677,2678,2679,2680,2681,2682,2683,3020,2973))"
        }
      }
    ]
  }
}