SELECT 
  1 
FROM 
  cscart_june_setupec_print_temp_designs 
WHERE 
  session_id = 'ZW3C-BK18-BI98-DJVR-4T5C-4RG5-N4F0-QABC' 
  AND product_id = 151 
  AND expires_at > 1781762744 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00068

JSON explain

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