SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b8c401298176105b2c3f11c99c972825a94d8b3d810661b42a7af0eb725745b' 
  AND token = 'EabVDyhMpIxCKzn5B8twD+iczgJEjCOYDM1+6OZiMTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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