SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3679590335a315087352ccaad1b7f593acee5c735d2f8de74005b756a16e5332' 
  AND token = 'kHCjDjqTo6e5Ll6QSRxjtAsw6TeQTUQUeIZAoj5QRLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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