SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92b75a7423fc7ba8756d7ecf00026e15712bf3b1577751e6c72736888a66710b' 
  AND token = 'tfHb7XFARB9ckRk6ZKfmABelsYpIJVAKIRuK6GzBi7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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