SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20c1d52dc287c5042200c3543896080a420ed5b51b224cb0672c9b77d4c81fa1' 
  AND token = 'rYtMwzsomYa41CDdqvqDvQRegy4eBe/YOyMyD20tWfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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