Sandbox

SELECT 
  1 
FROM 
  cscart_ec_print_temp_designs 
WHERE 
  session_id = 'ZK3Q-JZ9Y-MB1W-O6OC-ATLZ-8ERW-7HUA-LKFO' 
  AND product_id = 35 
  AND expires_at > 1770672523 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}