Sandbox

SELECT 
  1 
FROM 
  cscart_june_setupec_print_temp_designs 
WHERE 
  session_id = 'S4KJ-QLEF-TP64-APQK-UOD1-KVOU-7DWF-BKM1' 
  AND product_id = 21 
  AND expires_at > 1781878537 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00039

JSON explain

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