SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2521ae694cd6d86f843330b9c83a0c27a82ddf19188855e0ff7fa29c65a99d4' 
  AND token = 'HXXbIGx729AZFJZiKRF25hoKQZtsNhBjgw38Z8oXTzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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