SELECT 
  product_id 
FROM 
  cscart_product_popularity 
WHERE 
  product_id IN (
    376, 1612, 1613, 1614, 1615, 1616, 1617, 
    1618
  )

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_popularity",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "total"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 8,
      "filtered": 100,
      "attached_condition": "cscart_product_popularity.product_id in (376,1612,1613,1614,1615,1616,1617,1618)",
      "using_index": true
    }
  }
}