SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c55acfb36197d22452457262e8a60197ef46cc365a69d160fdee77e57e76ce' 
  AND token = 'zeTKtlgjI55b3JjCjvWvE07U8qlCXeqUb99yj1zf1CE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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