SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b14f1abb457cac360a2b974a596da57c89d147399dea171ed3172852a2629815' 
  AND token = '6jhTXMei0p9kfmyQDrtXsHjNIOgDU/+wjWgJG3rd7aQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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