SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f28d389eba5477559a2f03a937d0a494bdecd2ae99b7df6f87332f3d7f452ff' 
  AND token = '1uMxsuZcoFpxyRmJhm6cfI/wpGc6V0kxkfsc3RDBQ2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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