SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b9cbf4f9410e870a7d7183b090fb8dbe30f7b8111dcfdf3359a3d5c5f1845d' 
  AND token = 'jIl12xvgoYHnRGcKLXmqIAhlElMrnnA/4Q1/Z41dfhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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