SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '818151832117927402cecc07de96ea4571e1406b413eadd5c0dffb7295d7c931' 
  AND token = 'pjXjXRZcAzeVD5dIBeDkhMAGinTImteYkj2PsTnYyFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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