SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f03f81545791e538cb45a183545637bb5e274919325f14f6f720c1d9de18884b' 
  AND token = 'YxMQn8PXXNehEkeBef+j9RHv1HXQ7RSS6EAGCPL9nKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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