SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    3420, 3423, 3912, 3430, 3429, 3437, 3436, 
    3438, 6959, 3425, 6958, 6960, 6968, 
    6961, 6964, 6957, 6956, 6954, 6955, 
    6948, 3914, 3913, 6950, 6949, 3477, 
    3452, 3478, 3479, 3453, 3491, 3488, 
    3497, 3495, 3489, 3492, 3496, 3490, 
    3494, 6951, 3502, 3503, 3493, 3498, 
    3428, 3433, 3432, 3419, 3418, 6946, 
    6945, 3411, 3415, 3417, 6942, 3410, 
    3413, 3416, 6940, 3414, 6938, 6941, 
    6944, 3412, 6937, 6939, 6943, 3165, 
    3139, 3140, 6712, 6713, 3135, 5802, 
    6970, 6971, 6972, 6973, 6974, 6975, 
    3403, 3404, 3405, 3406, 3408, 3409, 
    6930, 6931, 6932, 6933, 6934, 6935, 
    6936, 3407, 2666, 3845, 2667
  )

Query time 0.00120

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "201.61"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 96,
          "rows_produced_per_join": 96,
          "filtered": "100.00",
          "index_condition": "(`gaseus`.`p`.`product_id` in (3420,3423,3912,3430,3429,3437,3436,3438,6959,3425,6958,6960,6968,6961,6964,6957,6956,6954,6955,6948,3914,3913,6950,6949,3477,3452,3478,3479,3453,3491,3488,3497,3495,3489,3492,3496,3490,3494,6951,3502,3503,3493,3498,3428,3433,3432,3419,3418,6946,6945,3411,3415,3417,6942,3410,3413,3416,6940,3414,6938,6941,6944,3412,6937,6939,6943,3165,3139,3140,6712,6713,3135,5802,6970,6971,6972,6973,6974,6975,3403,3404,3405,3406,3408,3409,6930,6931,6932,6933,6934,6935,6936,3407,2666,3845,2667))",
          "cost_info": {
            "read_cost": "57.61",
            "eval_cost": "9.60",
            "prefix_cost": "67.21",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "gaseus.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 96,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "24.00",
            "eval_cost": "9.60",
            "prefix_cost": "100.81",
            "data_read_per_join": "37K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": [
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "gaseus.p.group_id"
          ],
          "rows_examined_per_scan": 3,
          "rows_produced_per_join": 288,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "72.00",
            "eval_cost": "28.80",
            "prefix_cost": "201.61",
            "data_read_per_join": "29K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}