SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5be643a723c46580157ee4d5a0b43b948b3308abba2bc23173e7fd5cfbcddeac' 
  AND token = 'zD4ijXQrNPRsUDU0fbpR/I+JKMqCc5RyTf1Wr4aFpR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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