Sandbox

SELECT 
  1 
FROM 
  cscart_ec_print_temp_designs 
WHERE 
  session_id = 'RDFV-FW6O-YNXU-IS1H-1J9E-9N0M-U0BA-944T' 
  AND product_id = 35 
  AND expires_at > 1771073989 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00020

JSON explain

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