SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc4ad21ee7379590d3f6edaac6121f4105443ab87111816990383579ed3632b6' 
  AND token = 'qX0lRDdCDm9oyEhRsTrKpicdsFhj3MrL1OzROvxOtT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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