SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b533e94fbdff3aaff92e48f80e1a659118e3c3eccadf6dba02760da20bed4178' 
  AND token = 'saQxZxheIwE10LwfXLsPB5xEdAN5DzISjuABSDi/HNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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