SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff0cb61ecded6ed7e105c0b0bb47c4aa0b1f132eb92c90dc6df666a1da36872' 
  AND token = 'Olp9LHJnxEKE9+FXWi+DwoeSpLN5fF6xLslggfHXmUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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