SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cbc132a33470c6025fb95b39dff53bd55cc32de2c76004c9fc507c811fff388' 
  AND token = 'Zu0yr14xmB+bdJ2UJEb1UDApnIcV7TUEzeIIMAhNKZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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