SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2638588a882e7f67e4cb05575c827dc5233decda232cfbc13301e14a74970212' 
  AND token = 'cXU0BagpSslbq8podbAPfa0vDGHfk9jK1yDRbYJO1ZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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