SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94b850d9d44f4d3919a30f6ef043c63c56353c11f5b241ee552a12fa1cb176ee' 
  AND token = 'Ltjc2xyZq8kQuwSg/cbCjUH7Fe3jjr1ZyzlbXF1JQHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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