SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c6209adfebfe6927e4ffc483dae268bf01b47d7889708b7b31e561198885d9' 
  AND token = 'PjqwAKWw8YSeU2vwIsZuSZUbVUH0wMQsX6wL/qjUObE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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