SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acbc2d9e5f8eac2a6a76487350baaea3671cec7abfce8ba7764d34d27c8e0398' 
  AND token = 'WoQaqYL/DKSVYIwmyBywam4aDxZ4CSonKGpmbpPxZ+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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