SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cffb55983ca32580127b9a4d37a30cf95b20fcc79000d09faddff3f530472122' 
  AND token = 'swOdoAtYwBcWGnURb9Z+sF+59o7bd+bZDyTSpJqjFA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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