SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8935390e642bca16bd17daff9a10559830beb2629c36b2b7afb741319630059d' 
  AND token = 'EPG2gjVvHQdZ3vYyN5bB8PXS503MkEC47d/hRRWvq9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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