SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fceec62146f479d3fdb6b577be0508fa1a4ea0ed487f0d02ef6672f5bb2cd194' 
  AND token = 'GaZgTTdl0M9MRTdU2JrD5QMNqIWfH6xHXHokXwt1FIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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