SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b37ac821e4b9de156fbdd3060f761955f1666fffbfd403c23978ae649f1c7c02' 
  AND token = 'TgG9BDlKO1AvviJ+79cW8SmYz98Gqtj+lyd6NZXFsiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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