SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af6fac333f455e8de599b621824849e41ff8ddc57b901916bca7290b1f137654' 
  AND token = 'dHXskE30tiFLi/nylb3K+89/2TXY2DapZhmNKyOJ6xQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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