SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99c50a03c9e1d3dbf42701183fc8715b8584596eafd668cd42a79cd3ab0e9144' 
  AND token = 's1BmPRgH+qFa9z6EvUSytsm8ZPXKFN7MvA9YpDLL1CQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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