SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    51352, 51351, 96, 51354, 51353, 43, 51356, 
    51355, 44, 50998, 50999, 51000, 51001, 
    51002, 51003, 80, 51398, 51399
  )

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "22.06"
    },
    "table": {
      "table_name": "cscart_warehouses_sum_products_amount",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 39,
      "rows_produced_per_join": 39,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_warehouses_sum_products_amount`.`product_id` in (51352,51351,96,51354,51353,43,51356,51355,44,50998,50999,51000,51001,51002,51003,80,51398,51399))",
      "cost_info": {
        "read_cost": "18.16",
        "eval_cost": "3.90",
        "prefix_cost": "22.06",
        "data_read_per_join": "624"
      },
      "used_columns": [
        "product_id",
        "amount"
      ]
    }
  }
}