SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e420910f6a8fdf5f4e7e063184082941247696e8397357d711aee0a6209bef7' 
  AND token = '382YUazIAlMNPXOK1zo9psL+fvGg69jazd4DjiyF3CQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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