SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a38999a329530a3a3920c49de0c6b19446787bcc26068a89438a677be4dd96ef' 
  AND token = 'YgnEkxDo3qSamrkoYalR7M4FUJ1nwPBuwUaMhEw7qC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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