Sandbox

SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = '5FEC-CSTX-LHCL-9470-NRV1-1DK6-P6ZR-WL3X' 
  AND product_id = 240 
  AND expires_at > 1777137073 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00021

JSON explain

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