SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37b9ae184ab67b19e71a5e73545364990d55a63431da22f847175b661cf403c1' 
  AND token = 'pb1pf8qCexgtGOADwjVrHog7yq7wTTW61gDzOh7iztA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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