SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b2083b30f487da52bea644e3ab86bfec18059918841e3eaea27ebe0fd127d04' 
  AND token = 'wZaaywzz25fNYR3ik9HqFaTylA7SNeGnUBevbdZoZLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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