SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a51fd5d28c6ba7d1881bb208f27fc18787c1eb394d28656e64aa01ad09bcc99' 
  AND token = 'Rxlgkh6ovYYUZWQbu8FlZPXMs0J5rtcDEkS4ftV8IG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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