SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c68afc009a85a25872ed73942874cfdfbb325e58b10ab174ca3e00a31da42b49' 
  AND token = 'OwmwV/7RJW2s6EFsHQipcnXGOmxozkguSO7I3hXig0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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