SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518159fcf2a09153256b820bfeba2b3a9aeb4310570572e9ec88697b9bbbd717' 
  AND token = 'CdeMYy5T944fU2dSOoWlnhZgElnjPy/bWv7q/klclTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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