SELECT 
  product_id 
FROM 
  cscart_products 
WHERE 
  product_type = 'D'

Query time 0.00014

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "ALL",
      "rows": 3,
      "filtered": 100,
      "attached_condition": "cscart_products.product_type = 'D'"
    }
  }
}