SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = 'JG0M-6L9S-F0U1-SFP0-QTO1-1ZWJ-DIJV-SU1N' 
  AND product_id = 50 
  AND expires_at > 1778133207 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00025

JSON explain

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