SELECT 
  product_id, 
  amount 
FROM 
  cscart_warehouses_sum_products_amount 
WHERE 
  1 
  AND product_id IN (
    51019, 51014, 51045, 51025, 51029, 51060, 
    51063, 51020, 51027, 51067, 51031, 
    51062, 51028, 51033, 51026, 51042
  )

Query time 0.00069

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "17.06"
    },
    "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": 29,
      "rows_produced_per_join": 29,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_warehouses_sum_products_amount`.`product_id` in (51019,51014,51045,51025,51029,51060,51063,51020,51027,51067,51031,51062,51028,51033,51026,51042))",
      "cost_info": {
        "read_cost": "14.16",
        "eval_cost": "2.90",
        "prefix_cost": "17.06",
        "data_read_per_join": "464"
      },
      "used_columns": [
        "product_id",
        "amount"
      ]
    }
  }
}

Result

product_id amount
51014 1
51014 1
51019 4
51019 4
51020 5
51020 5
51025 3
51025 3
51026 5
51026 5
51027 2
51027 2
51028 3
51028 3
51029 1
51029 1
51031 2
51031 2
51033 1
51033 1
51042 5
51042 5
51045 5
51045 5
51060 20
51060 20
51062 4
51062 4
51063 5
51063 5
51067 5
51067 5