SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39dd2ebcc53b55a344fa79df17280aa7a7fc26407f5733ef58ac7b2a1a2db04' 
  AND token = 'qcBtDCWwKPzlPg+PcgXovwEVgOYZCM/Hf37NvsKqRpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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