SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a28cab214a9fcfebc35f61ba96a87f3d17e1afc39867173301dabf37a013b938' 
  AND token = 'VxmsUszJnuC+RXq5i3+2ZyWdb4FpUqGBZ/Wi5vJt5/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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