SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43fd29cfc212687e9c75696de5ef9492094907a26f51f978774c235eaa234256' 
  AND token = 'fOUdly5f/uRyiZkikXslTcAEJDUoCFQ7BSvu6cHERxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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