SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c514c645ec8ab1cdd671051f129075ce30569e28e626a1d7983f7bef269ce3dc' 
  AND token = 'zSEAWrTUWUDTc7QkbQaFf4AfPYtKQOrfSjeEKuzcY5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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