SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e318c336db6a60ecaf47bfe3a4576354ad5779008b6d406a5b1d3fe4c4e9f35' 
  AND token = 'YkWpQoXFsIWKSqmYboPpnpZZmgCn2zHHeDsAbjyQIaA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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