SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = '8UDX-FZB7-1W88-D23X-ZL4E-8OR2-JEJU-SB03' 
  AND product_id = 192 
  AND expires_at > 1777403987 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00037

JSON explain

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