SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da275a55223e3fc66b355f7c3d796bd1374b01acb22a25d31304854c104964ed' 
  AND token = '35pdQoPCeSMOG7NBaqejTxm9QXOmuk74FRs7jAQ4jYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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