SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3598cf22ad19642b715cef53ccfcb808397f8d2720ea14cee8033edd692d2e27' 
  AND token = 'MF/v4avr9zwK3wxZHpMBmS0H/sPig9A/YMZ3tWUXnKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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