SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    65660, 65883, 65938, 65884, 65892, 65896, 
    65895, 65937, 65888, 65956, 65838, 
    65890
  )

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 12,
      "filtered": 100,
      "attached_condition": "cscart_products.product_id in (65660,65883,65938,65884,65892,65896,65895,65937,65888,65956,65838,65890)"
    }
  }
}

Result