SELECT 
  * 
FROM 
  cscart_ec_products_plan_detail 
WHERE 
  product_id = 12

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.00"
    },
    "table": {
      "table_name": "cscart_ec_products_plan_detail",
      "access_type": "system",
      "rows_examined_per_scan": 1,
      "rows_produced_per_join": 1,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "0.00",
        "eval_cost": "0.20",
        "prefix_cost": "0.00",
        "data_read_per_join": "1K"
      },
      "used_columns": [
        "id",
        "product_id",
        "plan_name",
        "interval",
        "interval_count",
        "price",
        "paypal_plan_id",
        "global_plan_id"
      ]
    }
  }
}