SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6feaceaa6bd7f102c684b7e7cd72c3036232d0493a36a1d70d76312f11f8fba6' 
  AND token = 'pOqTD30FDJUvzfyAAsYw4QbkhXqBFoLeTci4SQAUQs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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