SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb27f9e76f46cc222dee11b260014ae2830a2824dbf506b11bda028e6131b263' 
  AND token = 'YaYofxISG0TAGjlMzCxAPRcElOICgU+LWV+J2tPywzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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