SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ace3c65219898729a1270b98ee6cb9c92126973e860a8972ab575e911f7be23' 
  AND token = '9nmREMsQ6GAr8kCbIo6IH0UNWDQvZgmkJVlGcYgFnek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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