SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9510569d2f46ef749d1611d019bd29aade79952f5d9d84ee99ddcc1cc6e0e2f7' 
  AND token = '3h6qCfWjyNpErq/bYg0qTvkMd0lEMgwJrwt8turzPz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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