SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd4a608f8fd1a931627f80371bc145a5edecb8418f461ecbdfc72c147594fcf0' 
  AND token = 'D3oJ+YhEmjxGnPS8VZL/tmmU6S9Ms9ng6g6nb1KJ4/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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