SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a838bad832e11eef18a465c6399a2dc99d801435d718f679a9a6a11e70c00a64' 
  AND token = 'NMJImuVxHwJzzq1WMdILUrdt7qr7i0bT7azdj/AieLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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