SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00815baab612f23933d3e465d02b2ccf7f1234a5bca4b6312012feb8d8d18123' 
  AND token = 'fikKDkcnKeepTMZCSdIxjyuipmdN8aKyFvzqZvw+YHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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