SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcbe9fe13a4224b750380884509c3289475c020f2701ceb2d853e9e849f66f6e' 
  AND token = 'o6XJ9DAMaa30It7qmxytgIbhzXc3ukBK8FjU7EHtGA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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