SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af68fcb66f703dc3f2c6d9609883fad9ca45ef857b208be3989c184abcc0819e' 
  AND token = 'k0L1SK+TlZspAARFUbo0a9SfRgIJEeIhXciPWWHpXGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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