SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ce3d1fc8d0c253db2df3e53722638706bc140c93abf525b233d02df9e5feed5' 
  AND token = 'A8HuIAHwV4hSAKXeQQeLCC2oZRmCE/8C1eM/AW2h1QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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