SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df0d28098c55bc5e29c0ece27c19ee6c42b3e5792bba415d12864433269a656d' 
  AND token = 'oZPVOwBgFOcip0q8ti9bsFnl+lyHgRnw6Ej3UyfSjns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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