SELECT 
  1 
FROM 
  cscart_aprilec_print_temp_designs 
WHERE 
  session_id = 'B2ZB-VF13-N9KD-YGKV-T0W6-H4S3-08UH-4JBS' 
  AND product_id = 90 
  AND expires_at > 1777986694 
  AND confirmed = 'Y' 
LIMIT 
  1

Query time 0.00038

JSON explain

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