SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b59f72f461c286891220f99a4936aced104b66eee3d188c62318aa3da22bffb' 
  AND token = 'TXwy/9cwZguQU3m4TDKsrvUsY/LppgUFq1eJXgxdejI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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