SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73ee2f3c9bb835809e7123b4732416153bc5068b0172d5e977366f2e90cd098b' 
  AND token = '0kqGyh2yaQFnEAiLzllmvRAvUGE3wke1+nhfEpdeoq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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