SELECT 
  product_id 
FROM 
  cscart_products 
WHERE 
  product_type = 'D'

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.02767171,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "ALL",
          "loops": 1,
          "rows": 102,
          "cost": 0.02767171,
          "filtered": 100,
          "attached_condition": "cscart_products.product_type = 'D'"
        }
      }
    ]
  }
}