SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a944cfe8667d44520624bb9617b600606f825994c2e84108886caf1d799999ea' 
  AND token = 'fuS87qqCEDB3N1IZJrOOCV5OnyFURaYD+sijAWVjSdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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