SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '572dc250f3ad52a1c5ffc11bb6d59e744cc76091442fb092cf78207a9b3fcdaf' 
  AND token = 'PpUroUrAG8CmoxClMe68RkWI7CDfoL2NxeW0k7X5kJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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