SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6764db9b260f38638ec7881522adebd1dd5120b12c1da91d9ef78f27192adbe' 
  AND token = 'JCk41BvXpVPsn1i6nfcz2gMGJov+OtHaJU36Ya36JhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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