SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27f75b3b5f6452ab67a4ead5805dd5f806b97394d31d6c44c428862dc2727e65' 
  AND token = 'QMh0SEtbOLYKUNmV//tgSs7Yl2UdPyOmOJJCT1uonv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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