SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '898bc18544f4167ee670332e1ed3c0c4e270d738eee76fabe46ddfb402c1cbb3' 
  AND token = 'xArkFDGu4dkrQqePUYA+tPWdNV9cpUYrLGMPhHgZKxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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