SELECT 
  cscart_product_sales.product_id, 
  amount AS sales_amount 
FROM 
  cscart_product_sales 
  LEFT JOIN cscart_products_categories ON cscart_products_categories.product_id = cscart_product_sales.product_id 
  AND cscart_products_categories.category_id = cscart_product_sales.category_id 
WHERE 
  cscart_product_sales.product_id IN (
    13860, 13439, 13440, 14041, 13441, 13876, 
    13879, 15167, 16346, 14032, 14033, 
    14034, 16334, 16348, 13442, 13443, 
    15749, 14660, 13444, 14149, 14650, 
    14024, 13896, 16347
  ) 
  AND cscart_products_categories.link_type = 'M'

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.02972721,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_sales",
          "access_type": "index",
          "possible_keys": ["PRIMARY", "pa"],
          "key": "pa",
          "key_length": "6",
          "used_key_parts": ["product_id", "amount"],
          "loops": 1,
          "rows": 21,
          "cost": 0.009726305,
          "filtered": 100,
          "attached_condition": "cscart_product_sales.product_id in (13860,13439,13440,14041,13441,13876,13879,15167,16346,14032,14033,14034,16334,16348,13442,13443,15749,14660,13444,14149,14650,14024,13896,16347)",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "cscart_products_categories",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "link_type", "pt"],
          "key": "link_type",
          "key_length": "9",
          "used_key_parts": ["link_type", "category_id", "product_id"],
          "ref": [
            "const",
            "u508912950_dev_2025.cscart_product_sales.category_id",
            "u508912950_dev_2025.cscart_product_sales.product_id"
          ],
          "loops": 21,
          "rows": 1,
          "cost": 0.020000905,
          "filtered": 100,
          "attached_condition": "cscart_products_categories.link_type = 'M'",
          "using_index": true
        }
      }
    ]
  }
}