SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14b731866e1dab7cbff6f663b019ed83378f3d0f4852de960588a65725d8f4f1' 
  AND token = 'tAc2hMsZgZhkrwUFvJlcqoj9Nc+xJiQ2s4Ja6gxlFg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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