SELECT 
  products.product_id 
FROM 
  cscart_products AS products 
WHERE 
  products.master_product_id = 91 
  AND products.status IN ('A') 
  AND products.amount > 0

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.001792605,
    "nested_loop": [
      {
        "table": {
          "table_name": "products",
          "access_type": "ref",
          "possible_keys": [
            "status",
            "idx_master_product_id",
            "wdbi_master_product_id_master_product_status_produc_611007cab252",
            "wdbi_master_product_id_master_product_status_produc_37d8c9a2112a",
            "wdbi_master_product_id_master_product_status_status_1d4dcd83320a",
            "wdbi_master_product_id_master_product_status_produc_909a0cf2d55b",
            "wdbi_master_product_id_master_product_status_status_ff7ba2ae2fb0"
          ],
          "key": "wdbi_master_product_id_master_product_status_status_ff7ba2ae2fb0",
          "key_length": "4",
          "used_key_parts": ["master_product_id"],
          "ref": ["const"],
          "loops": 1,
          "rows": 1,
          "cost": 0.001792605,
          "filtered": 100,
          "attached_condition": "products.`status` = 'A' and products.amount > 0",
          "using_index": true
        }
      }
    ]
  }
}