SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '376ec641dafd0f3925c4ba888590da089f9a3b6be89b95c7262ef482301c914e' 
  AND token = 'O5WjCdfWOzL464U2ikhhkDJSvIBYQjNNYSeAvvfE0Q8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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