SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03880d600ab4678293dc5ee69c27e4cb787dbfe65f8c9bb84747ee422385499' 
  AND token = 'HLdNizYwof5Ed0r18fvXXoJkRyghVpUOdmeYPI+PDd4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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