SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '073360b99c38e06c6554dd65a76dc36e9da132ece9936285293a114187f76c0b' 
  AND token = 'VDhGyXQJMT5xgAykut5VqdRehFfSkTJTOVAhlyBU1qM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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