SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9621d799d490ddfe327f55b3f079adbe995e6a73575874aef9aac2ee7c742fc4' 
  AND token = 'MDFmxDE+VtJJ3UnflshpPFvNvRthPXDHHnBTElZcaeI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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