SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847932c78b9bd79d37eb241d539d1b22c97eda3155619537cb229f921ebd055f' 
  AND token = 'jmiPdM5FQjVpXRg0MhCd21E7CSNjE9xP68N5OBYfbvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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