SELECT 
  1 
FROM 
  cscart_june_setupec_print_temp_designs 
WHERE 
  session_id = 'JAVP-0NLQ-I57Q-68OR-CAQ2-2700-9S08-GPF8' 
  AND product_id = 54 
  AND expires_at > 1781891875 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00023

JSON explain

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