SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c2619fae8323b3bb31cfd05113c0df835c621eaea5eef78ef76c0a28dee546' 
  AND token = 'qpQkftbjpxmaxAXr4JpUiYvS18hu2z+oSgMu+txtd+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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