SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a580e276cea6280473d517369d2a2a1a2e2350a029adcaaf8feb84ae7c4971a' 
  AND token = 'OuMqpgNgyvLdsAlpOUPcU8luxPfNyAJEDueTZP5sVzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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