SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f46adb040640bef13f274e390f31cf8c4f03c534d453417d6b285845563a88a0' 
  AND token = 'wxH+zICjYzKanHvnoMqVN0wHhVt7jS+ysVgbtnUU+Nw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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