SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39b24e4e9b459978e9c77bfef368505e79dca77b618ab775ea110388c1e29327' 
  AND token = 'saAjpb3tsaNQplKvcqxaYkhN9Y/lnWbqQXKokFJlMps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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