SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3c4cd7766e8c3a3c50b7e52c16243f6ca232a50091fed9bee33157beee61a45' 
  AND token = 'x8ztsLKA8GQRrMvIvWroUsMuFuWZ/a7jjhFJvYBHNf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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