SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756fbec682dd79607408e2dc48337c12a5b236f6a16fcc793bbefdbe28fd133d' 
  AND token = 'RWSaKVgpKHyC49uix4YojsM46LQ7yT9g7ayPycXI5bU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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