SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c858f057f2a66d5bfc879617c1dbcd3af181cb96120bec517bb10fa4650d29' 
  AND token = 'UfI6nTlL1uXF2jD9Z4MzmoP8RXxsc+HQfoDC9qTjG3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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